Performance of the CMS Hadron Calorimeter with Cosmic Ray ... · CMS PAPER CFT-09-009 CMS Paper 2010/01/01 Performance of the CMS Hadron Calorimeter with Cosmic Ray Muons and LHC

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Year: 2010

Performance of the CMS hadron calorimeter with cosmic ray muons andLHC beam data

CMS Collaboration ; Amsler, C ; Chiochia, V ; De Visscher, S

Abstract: The CMS Hadron Calorimeter in the barrel, endcap and forward regions is fully commissioned.Cosmic ray data were taken with and without magnetic field at the surface hall and after installation inthe experimental hall, hundred meters underground. Various measurements were also performed duringthe few days of beam in the LHC in September 2008. Calibration parameters were extracted, and theenergy response of the HCAL determined from test beam data has been checked.

DOI: https://doi.org/10.1088/1748-0221/5/03/T03012

Posted at the Zurich Open Repository and Archive, University of ZurichZORA URL: https://doi.org/10.5167/uzh-45572Journal ArticleAccepted Version

Originally published at:CMS Collaboration; Amsler, C; Chiochia, V; De Visscher, S (2010). Performance of the CMS hadroncalorimeter with cosmic ray muons and LHC beam data. Journal of Instrumentation, 5(3):T03012.DOI: https://doi.org/10.1088/1748-0221/5/03/T03012

CMS PAPER CFT-09-009

CMS Paper

2010/01/01

Performance of the CMS Hadron Calorimeter with CosmicRay Muons and LHC Beam Data

The CMS Collaboration∗

Abstract

The CMS Hadron Calorimeter in the barrel, endcap and forward regions is fully com-missioned. Cosmic ray data were taken with and without magnetic field at the sur-face hall and after installation in the experimental hall, hundred meters underground.Various measurements were also performed during the few days of beam in the LHCin September 2008. Calibration parameters were extracted, and the energy responseof the HCAL determined from test beam data has been checked.

∗See Appendix A for the list of collaboration members

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1 Introduction

The primary goal of the Compact Muon Solenoid (CMS) experiment [1] is to explore particlephysics at the TeV energy scale exploiting the proton-proton collisions delivered by the LargeHadron Collider (LHC) [2]. This paper describes the performance of the CMS Hadron Calor-imeter (HCAL). The measurement of the detector response started with the characterizationand calibration of representative samples of all detector components in the laboratory using atest beam [3–6]. After assembly of the detector, the calibration was improved and validatedusing cosmic ray muons and LHC beam. The cosmic ray muon data also allowed the testingof the whole data acquisition process, up to the event reconstruction and analysis. The vali-dation includes comparisons with Monte Carlo simulation studies, which are fundamental inunderstanding the detailed performance of the detector.

CMS has taken cosmic ray muon data with and without magnetic field at the surface hallin 2006, during the Magnet Test and Cosmic Challenge (MTCC) described in Ref. [7]. Re-cently, data were taken in the underground cavern at ∼ 100 m depth with the magnet off in2007 (CRUZET: Cosmic RUn at ZEro Tesla) and with the magnet on in 2008 (CRAFT: CosmicRun At Four Tesla [8]).

In September 2008, the LHC delivered a single circulating beam of 450 GeV/c protons for afew days. In addition, as part of the commissioning of the LHC, the beam was also sent ontocollimator targets creating accelerator produced muons. These “beam splash” events provedvery useful to determine the relative timing of various the HCAL systems [9], as well as tovalidate the performance of several components.

Knowledge of the HCAL performance acquired during CRAFT and with beam splash data willprove crucial to the understanding of data in the early stages of LHC operation. This will allowthe timely analysis of benchmark QCD processes and of known missing energy signals. Anysearch for new phenomena must be grounded on these benchmark analyses.

The paper is structured as follows. Section 2 provides a brief description of the Hadron Calor-imeter. Section 3 discusses the impact of the magnetic field on the various parts of the HCALsubsystems. The characteristics of the basic behavior of all the HCAL subsystems and the opti-mization of key hardware settings are summarized in Section 4. Finally, Section 5 discusses thecalibration improvements obtained with the various data samples.

2 CMS Hadron Calorimeter

The main CMS subsystems, in increasing radial distance from the beam intersection point (IP),are the silicon pixel and silicon strip tracker, the electromagnetic calorimeter, the hadron calor-imeter, and finally the muon system. In addition, in the forward direction there are two spe-cialized calorimeters [1] that did not participate in the cosmic ray runs and are not discussedin this paper. The detector is symmetric for positive and negative z coordinates, the z axis be-ing along the beam direction with z = 0 at the IP. The polar angle, θ, is measured from the zdirection, and the azimuthal angle, φ, is measured in the transverse plane. The pseudorapidityis η ≡ − ln tan(θ/2).The HCAL includes four distinct subsystems: the barrel (HB), endcap (HE), outer (HO) andforward (HF) calorimeters (see Fig. 1). HB and HE, which are inside the cryostat of the CMSsuperconducting solenoid that provides a 3.8 T magnetic field, are sampling calorimeters wherethe absorber material is brass and the active material is scintillator. The sampling fraction isabout 7%. HB and HE are separated by a gap which is located approximately at a polar angle

2 2 CMS Hadron Calorimeter

of 57 degrees but is not projective to the center of CMS, in order to minimize the effect of theuninstrumented gap. HB covers the |η| range from zero to approximately 1.4; the |η| rangebetween 1.3 and 1.4 is shared by HB and HE; HE covers |η| from 1.3 to 3.0. HB is built of18 wedges, each of which covers 20 degrees in φ, and are divided in 5 degree sectors. HE ismade of brass disks, interleaved with scintillator wedges which cover 20 degrees in φ, whichin turn are divided in four 5 degree sectors. Because of the space constraint within the magnetcryostat, the HB thickness is limited to 5.8 hadronic interaction lengths at η = 0 and increases to10 interaction lengths at |η| = 1.2. To catch the energy leakage from HB, layers of scintillatorsare placed outside the solenoid cryostat: they constitute HO. About 5% of all hadrons above100 GeV deposit energy in HO. In φ, HO has a 12-fold structure, with each 30 degree componentbeing divided in six 5 degree sectors. In η, HO is composed of five “rings”, which follow thestructure of the magnet return yoke and of the muon chambers. Ring 0 covers the η rangebetween -0.35 and 0.35, Rings ±1 cover the |η| range between 0.35 and 0.87, and Rings ±2cover the |η| range between 0.87 and 1.2. The quartz fiber and steel HF calorimeter, with fibersparallel to the beam direction, covers the forward region of |η|, between 3.0 and 5.2. HF isconstructed in wedges of 20 degrees and each wedge contains two φ sectors of 10 degrees.The calorimeter tower segmentation in η and φ of HB, HE and HO subsystems is 0.087×0.087except in HE for |η| above 1.74, where the η segmentation ranges from 0.09 to 0.35 and the φsegmentation is 0.175. The HF segmentation is 0.175×0.175 except for |η| above 4.7, where thesegmentation is 0.175×0.35.

Figure 1: The CMS HCAL detector (quarter slice). “FEE” indicates the locations of the FrontEnd Electronics for HB and HE. The signals of the tower segments with the same color areadded optically, to provide the HCAL “longitudinal” segmentation. HB, HE and HF are builtof 36 identical azimuthal wedges (∆φ = 20 degrees).

Figure 1 shows a schematic quarter view of the hadron calorimeter system in the barrel, endcapand forward regions. Also shown are the locations of some of the Front End Electronics (FEE).The HF FEEs (not shown) are placed around a ring at |η| = 3 (tower number 29) and HOFEEs are located inside the muon detectors at various locations. Each HB and HE tower has 17scintillator layers, except near the overlap region between HB and HE. Each scintillator tile of atower is read out by an embedded wavelength shifting fiber and the signals are added optically.The color scheme in Fig. 1 denotes the longitudinal segmentation of the read out; all layersshown with the same color in one η tower are summed. The optical signals for HB, HE and HO

3

are detected by hybrid photodiodes (HPD) with 19 independent pixels; 18 for read out of fibersand one for monitoring. The HPDs are designed to work inside the magnetic field, providedtheir axes are aligned with the magnetic field. This alignment is adequate for HB and HE, butit was found that the HO HPDs were off by as much as 40 degrees. This misalignment was dueto the difficulty in simulating the magnetic field inside the return yoke. Therefore, an effort isunder way to study the possible replacement of the HO HPDs with silicon photomultipliersthat are insensitive to magnetic fields and have a better signal to noise discrimination.

In HF, quartz fibers of two different lengths are embedded in the steel, and are read separately.The calorimeter is thus functionally subdivided into two longitudinal segments (not shown inFig. 1). Long fibers (165 cm ≈ 10 interaction lengths) measure the total signal coming from thefull material length, whereas short fibers measure the energy deposition after 22 cm of steel.This allows the separation of showers generated by electrons and photons from those gen-erated by hadrons. The photodetectors for HF are eight-stage photomultipliers (PMT) with aborosilicate glass window, which register the Cherenkov light produced by the charged showerparticles in the quartz fibers.

The signals from both types of photodetectors are read by a custom-designed chip, which per-forms charge integration and encoding (QIE) [4]. The QIE is a non-linear multi-range analog todigital converter (ADC) that provides approximately constant fractional precision over a widedynamic range. For each channel, the measured ADC value is converted into a charge mea-sured in femtocoulomb (fC), using a conversion factor that was determined in the laboratoryby charge injection into the QIE.

Each subsystem is equipped with laser and light emitting diodes (LED), for monitoring andcalibration. In addition, the response of each HB and HE scintillator tile of each layer and eachHF fiber can be measured using radioactive sources mounted on the tip of a moving wire [10].

The Electromagnetic Calorimeter (ECAL), made of lead tungstate crystals, is situated in frontof HB and HE. The response and resolution of the CMS calorimeter system depends on boththe ECAL and the HCAL, as most particles start showering in the ECAL. The hadronic to elec-tromagnetic (π/e) response ratios of the ECAL and the HCAL are different: typical values ofπ/e for the ECAL and the HCAL are 0.61 and 0.80 at 10 GeV/c, and 0.75 and 0.85 at 100 GeV/c,respectively [6]. The ECAL and the HCAL fraction of the energy deposited in each calorimetervaries non-linearly with energy and, as a result, the raw energy measurements require substan-tial corrections. Results from test beam studies are reported in [3–6].

Parts of the various HCAL subsystems were exposed to beams of electrons, pions, protonsand muons, to measure their characteristics and to obtain a reference calibration. An ECALmodule was also included in the test beam setup. The hadronic energy resolution of the barrel

HCAL and ECAL combination being parameterized as σ/E = a/√

E ⊕ b, where a correspondsto a stochastic term and b to a constant term, one measures a = 0.847 ± 0.016 GeV 12 and b =0.074 ± 0.008 [4], with E measured in GeV. The energy resolution in the endcaps is similar tothat in the barrel. The corresponding values for HF are a = 1.98 GeV

12 and b = 0.09 [3]. Since

the forward jets typically have very high energies, the stochastic term may be higher for HFthan for the other calorimeters, while still providing the required energy resolution [3].

3 Impact of the Magnetic Field on the HCAL Response

About 270 million cosmic ray muons were recorded during CRAFT with the magnetic fieldon. Typically, a muon event is triggered by the muon chambers and the muon momentum is

4 3 Impact of the Magnetic Field on the HCAL Response

measured by the central tracker and muon chambers. Clean signals were measured in most ofthe HCAL towers. The cosmic ray muons are used to measure the HPD gain to an accuracy ofabout 5% for HB and HO towers, and 10% for HE. Calibration corrections based on the studyof the cosmic ray muon samples have been derived and applied for HB and HO, as discussedin Section 5.

Brightening corrections, of about 8-10%, applied to HB and HE calibration parameters to takeinto account the effects of the magnetic field were already obtained during MTCC, where itwas possible to perform precise measurements using radioactive sources [1]. Cosmic ray muondata from CRUZET and CRAFT allowed to test these corrections and to study the impact of thestrong magnetic field in other parts of the HCAL system.

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3.1 The Barrel and Endcap Hadron Calorimeters

A single muon traversing the HCAL deposits a few GeV in HB and HE. Figure 2 shows theenergy deposited in HB and HE by muons with momenta above 7 GeV/c, during CRAFT withthe 3.8 T magnetic field. The means are consistent with the muon minimum ionizing signalsmeasured for segments of the calorimeters in test beams [4, 6], without magnetic field, for awide momentum range after taking into account magnetic field effects, correcting the signalfor the muon path length and normalizing to the thickness of HB at η = 0. The width of thedistributions of the cosmic ray muons are broadened by the momentum spread of cosmic raymuons, since the energy deposition increases with momentum due to the relativistic rise. Themeasurement of the energy deposition by cosmic ray muons is performed using either the elec-tron or the pion calibration of the calorimeter. As an example, the mean energy deposition of150 GeV/c muons is calculated to be 2.4 GeV (2.8 GeV) if the electron (pion) calibration is used.For Fig. 2, the pion calibration was used. The average values of the energy deposition is lowerthan 2.8 GeV because the average muon momenta is well below 100 GeV/c (see momentumspectrum given in Fig. 10).

3.1 The Barrel and Endcap Hadron Calorimeters 5

It is known [11–15], that the presence of a magnetic field increases the signal measured in scin-tillator based calorimeters. There are three sources contributing to this effect. The first of themis due to a chemical effect that causes an intrinsic brightness of the scintillator. Brighteningis due to the polymer base of the scintillator and saturates at about 2 T. The maximum signalincrease due to brightness ranges between 5% and 8%, depending on the composition of theplastic [15]. The field value at HB and HE is 3.8 T, which is well above the saturation value.The second source of signal increase is the curling of knock-on electrons in the magnetic field,which results in an increased path length of the electrons, and enhances the signal by 1-2%.Therefore, the signal increase depends on the nature of the particle impinging on the calori-meter, on the geometry and on the strength of the magnetic field. For this effect, the specificorientation of the magnetic field relative to the absorber plates is thus important and is differ-ent for HB and HE. At the LHC, the directions of particles emitted from the IP are essentiallynormal to the scintillator plane, the magnetic field direction is parallel to the scintillator planein HB and perpendicular in HE. Previous measurements [15] and this study showed that thelight yield increase due to the magnetic field is the same for muons and for particles from ra-dioactive sources, while another complementary study [15] showed that the effect is differentfor pions and electrons, as electrons produce more knock-on electrons than pions. There is athird effect due to the HPD geometry. When a muon passes through a single tower, all the pho-tons impinge on one single HPD pixel. However, the electrons from the photocathode spreadout and up to 2% of the signal is measured in neighboring pixels, a phenomenon called crosstalk. The magnetic field helps in reducing this cross talk, but any misalignment of the HPD axiswith respect to the magnetic field axis increases the cross talk.

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Figure 3: Ratio of the scintillator signals in a single layer with magnetic field on and off, mea-sured using a radioactive source during MTCC. The left figure is for polystyrene (PS) in HBand the right figure is PVT (filled squares) and PS (open squares) in HE. The horizontal linesrepresent the averages of each data set. The difference for PS between HB and HE is due to thecurling of the knock-on electrons and the magnetic field direction.

The magnetic field effect on the HCAL was observed by comparing the measurements per-formed with a moving radioactive wire source, with field on and with field off during theMTCC. The inners layer (Layer 0) of HB and HE and all layers of HO are made of 1 cm thickpolymer polyvinyl toluene (PVT); all other layers of HB and HE are made of 0.4 cm thick poly-mer polystyrene (PS). Figure 3 shows the measurements performed at several magnetic fieldvalues for a typical polystyrene layer of HB (left) and for two layers of HE (right), one PVT andone PS. The PVT layer of HB was not installed during MTCC. The magnetic field effect on PS of9.4% measured in HB during MTCC agrees well with the expected value. The 2% difference in

6 3 Impact of the Magnetic Field on the HCAL Response

brightening between PVT and PS, shown in Fig. 3 (right), was also observed in an independentstudy [15]. For HE, a signal enhancement of about 6% is due to the increased brighteness of thepolymer polystyrene, and the rest is due to the path length of the knock-on electrons. The com-parison of CRAFT and CRUZET data reveals a net signal enhancement at 3.8 T of 1.090 ± 0.005for HB and 1.084 ± 0.013 for HE, consistent with the MTCC measurements of 1.094 ± 0.001 forHB and 1.080 ± 0.002 for HE.

3.2 The Outer Hadron Calorimeter

All scintillator layers in HO are made of 1 cm thick PVT. Ring 0 has two scintillator layers, whileRings 1 and 2 have a single scintillator. Figure 4 (left) shows the field strength at the positionwhere the scintillators are located. The first scintillator layer of Ring 0, at a radius of 3.82 m,is located in a region with a very small magnetic field. The signals in the two layers in Ring 0are added optically and the brightening effect is the average of the effects in the two scintillatorlayers. The other scintillator layers are at a radial distance of 4.07 m from the beam line, wherethe magnetic field is more important. The scintillator brightening for Ring 0 is about 1%, andfor Rings 1 and 2 it varies between 2% and 4%. This is to be compared to the 8-10% effectobserved in HB and HE above 2 T.

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Figure 4: Left: Magnetic field strength at the location of the HO scintillators, as calculated withthe TOSCA program [16]. The vertical lines indicate the ring borders. Ring 0 has two scintillatorlayers, at radii 3.82 m and 4.07 m, respectively. Right: Pedestal and cosmic ray muon signal inRing 0 of HO.

Cosmic ray muon signals are observed in all rings of HO. In Ring 0, with two scintillator layers,the signals are twice as large as in Rings 1 and 2. Figure 4 (right) shows the distributions of thepedestal and the pedestal subtracted muon signal in Ring 0.

3.3 The Forward Hadron Calorimeter

The magnetic field strength in the HF region is significantly reduced compared to that in theHB and HE regions, allowing the use of conventional PMTs.

During CRAFT, the magnetic field at the PMT locations was measured to be less than 0.03 T,and proper PMT operation was verified at full magnet current. Each PMT is shielded withindividual tubes made of a nickel-iron alloy and of soft iron. HF was fully operational andstable during CRAFT and the LHC startup.

7

In the CMS cavern, the number of cosmic ray muons decreases significantly with increasingincidence angle relative to the vertical direction. Therefore, it was not possible to validate thecalibration of HF channels with the CRAFT data, due to the lack of muons in the horizontaldirection.

The LHC startup data from September 2008, however, proved useful in validating the calibra-tion constants, and will be discussed in Section 5. Occasional abnormally large signals werefound in individual HF channels during the LHC startup. The signals were found to be dueto muons striking directly the window faces of individual PMTs. Algorithms for rejecting suchabnormal signals, by comparing the energies reconstructed from long and short fibers with thesame (η, φ) values, were subsequently developed based on these data [17]. The LHC beam halodata show that the current algorithms can reduce the rate of such abnormal signals by a factorof one thousand.

4 Optimization of the HCAL Operation using CRAFT Data

This section describes the information obtained from CRAFT about noise levels, detector stabil-ity and optimization of hardware settings, like high voltage and zero-suppression parameters,which could influence the HCAL energy resolution.

The HCAL has a total of 2592 channels in HB, 2592 in HE, 1728 in HF and 2160 in HO. At thebeginning of CRAFT, 99.3% of HB, HE and HF, and 95.5% of HO channels were operational.About 75% of the non-operating channels had photodetector (HPD or PMT) problems and therest had electronics failures of various types.

Several HPDs, about 10% of the total, functioned poorly when the magnetic field reached fullstrength. The high voltage for those channels was either reduced by 1.5 kV, leading to a ∼ 30%reduction in gain, or was completely turned off. After this action was taken, 87% of the HCALwas operating at the nominal high voltage of 7.5 kV both for the barrel and the endcaps. Noevidence of further degradation of HPD functioning was observed during CRAFT. In HF, whichemploys PMTs, the high voltage was set at 1.25 kV as originally planned.

The problematic HPDs were replaced after CRAFT. As of September 2009, all the channels inthe barrel, endcap and forward regions are operational at full magnetic field, while the numberof non-operational channels in HO is at the level of 2%. As a precaution, the nominal highvoltage during LHC collisions will be set 0.5 kV lower than in CRAFT for the barrel and theendcaps, at a cost of a 12% reduction in gain. The impact on jet energy resolution is small, ofthe order of 5%.

4.1 Performance of Photodetectors and Impact on the Trigger

During CRAFT, the rate of HPD noise replicating an energy deposit of 20 GeV or more in asingle channel was below 0.2 Hz [17], after the malfunctioning HPDs were excluded. Figure 5shows the measured total noise rate for all trigger towers in the barrel and the endcaps, as afunction of the energy threshold. The signals of the longitudinal segments of a tower are addedto form a trigger tower in HB, in HB-HE interface region and in HE (Fig. 1). Three sourcescontribute to this noise rate [17]: (a) the ion feedback inside the HPD (two to three neighbor-ing HPD pixels with energy greater than 1 GeV), which affects mainly single channels, (b) thenoise from the whole HPD, which affects 18 channels simultaneously (all HPD pixels with en-ergy greater than 1 GeV), and (c) coherent noise in a readout box (RBX), which affects a fullset of 72 channels (all channels with energy greater than 1 GeV); one readout box includes thesignals from four HPDs. The ion feedback is predominantly caused by a thermally emitted

8 4 Optimization of the HCAL Operation using CRAFT Data

electron that ionizes the residual gas inside the HPD acceleration gap. The ion is acceleratedback to the cathode and liberates further electrons, causing a signal equivalent to many pho-toelectrons. Misalignment of the HPD axis with respect to the axis of the solenoidal field canreduce the voltage of the HPD above which electrical discharges can occur. This can lead to anavalanche of secondary electrons, producing significant energy deposition in a large numberof channels within an HPD. This is the main noise contribution above 100 GeV and is referredto as “HPD discharge”. The cause of the readout box coherent noise is not yet understood, butmeasurements show that it does not have an impact on the trigger and can be easily identifiedduring the event reconstruction.

The HPD noise, with or without magnetic field, has a small impact on the total trigger rate. Forexample, without magnetic field and with a threshold of 10 GeV, the HCAL self-trigger rate is130 Hz; at full field the rate increases by 40 Hz. This is to be compared with the 100 kHz triggerrate expected during collisions. Furthermore, the rate decreases rapidly as a function of theapplied threshold, as seen in Fig. 5.

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Special triggers to monitor the HPD noise rate, offline software to identify the correspond-ing atypical signals at the event reconstruction level [17], and the corresponding simulationtools have been developed and are available. Initial tests on data show that the algorithms foridentifying noise and problematic channels correctly mark both persistent and sporadic knownproblems with high efficiency.

4.2 Performance of Readout Electronics and Impact on Energy Thresholds

The electronic noise and the pedestals in the QIE chips were found to be stable during CRAFT.The QIE chips read the signal over four time intervals of 25 ns each, using four pipeline-channels (numbered 0 to 3), and output four ADC values; the cycle repeats every 100 ns. Foreach QIE one measures four pedestal values of a few ADC counts each (one for each 25 ns timeinterval), which are subtracted from the corresponding signal. The left plot in Fig. 6 shows thevalues of the four pedestals and their averages for a particular HB tower, over a period of ten

4.2 Performance of Readout Electronics and Impact on Energy Thresholds 9

days. There is a small variation of the individual pipeline-channel pedestals over time, with astrong anti-correlation among them. The average of the four pedestals does not change overthis time period.

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sum four TS at low luminosity and two TS at high luminosity. The single channel noise at7.5 kV for 1 TS is 140 and 200 MeV for HB and HE, respectively.

The four pedestal values are correlated due to the integration of the pulse shaper, as demon-strated in the right plot of Fig. 6. This figure shows the observed noise averaged over a variablenumber n (from 1 to 9) of 25 ns time periods, compared to the increase as

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absence of correlations. These noise correlations have been included in the HCAL simulation.

The width of the pedestal distribution allows one to estimate the QIE electronic noise. Forexample, the measured electronic noise during CRAFT in a single time slice corresponds toan equivalent energy in a tower of 140 MeV for HB, 200 MeV for HE, 280 MeV for HO and370 MeV for HF (the larger HF noise remains small compared to the energy corresponding to asingle photoelectron, 4 GeV, and to the typical energies of particles impinging HF). The increasewhen integrating over more than one time slice is modest, as can be inferred from Fig. 6 (right).

The HCAL information obtained from a tower is not recorded if the signal is below a thresh-old, that is, the HCAL data are “zero-suppressed”. The information of a tower is kept onlyif the sum of ADC counts in two adjacent time slices is larger than 2 counts above pedestalfor HB, 3 counts for HE/HO, and 4 counts for HF. After taking into account the final highvoltage settings planned for collision data, these thresholds correspond to ∼400 MeV for HB,∼700 MeV for HE, ∼1 GeV for Ring 0 of HO, and ∼1 GeV for HF. These threshold values wereselected such that the HCAL occupancy is reduced to about 20% at the nominal LHC luminos-ity. Since some towers, which contain little energy, are eliminated by zero-suppression, this canreduce the measurement accuracy. However, since the energy thresholds for zero-suppressionare well below the energy threshold applied in the jet reconstruction, and since a shower isdistributed over many towers, zero-suppression will have little effect on jet and single high en-ergy hadron energy measurements. It can, however, affect the HCAL energy measurement forlow-momentum muons (pµ < 10 GeV/c) traversing a single tower and all muons traversing

10 5 Calibrations using Cosmic Ray Muons and LHC Beams

multiple towers.

5 Calibrations using Cosmic Ray Muons and LHC Beams

The calibration of the HCAL has been performed using several techniques. First, test beamsetups were used to determine, for parts of the HCAL subsystems, the detector response toradioactive sources and to electrons, muons and hadrons of known momenta. Then, the in-tercalibrations of all channels in HB, HE, and HF were performed with radioactive sourcesmounted on moving wires, exactly as was done in the test beam setups. These source mea-surements also propagate the absolute energy scale for each subsystem. The energy scale forthe reference Co60 source was made with respect to 50 GeV/c pions in the case of HB and HE,while for HF 100 GeV/c electrons were used.

A total of 31 beam splash events from the beam arriving from the +z side and 35 events from the−z side were recorded during the 2008 LHC commissioning exercise, with the CMS magneticfield off. In these events, muons from secondary decays penetrated the detector. Since thescintillator planes of HB and HO are parallel to the beam line, the muons from splash eventstraverse the full length of the scintillators giving a very large signal. The splash events couldnot be used to study the absolute energy scale calibration because their energy and muon fluxis not accurately known. However, these events were helpful for measuring the relative scalebetween φ sectors and between the ±z halves of HB and the two HE endcaps.The initial calibration obtained from measurements with radioactive sources was tested, andin some cases improved, using cosmic ray muons and the beam splash events for a significantfraction of HB channels. However, since cosmic ray muons in the CMS cavern are essentiallyvertical, HB φ sectors in the horizontal plane near φ = 0◦ (sectors 71, 72, 1 to 4) and nearφ = 180◦ (sectors 33 to 38) were not included in this study, while in HO all channels werecalibrated using cosmic ray muons. All channels in HE and HF were mainly tested with beamsplash events.

To ensure good energy measurement, only events collected without zero-suppression are usedin the calibration studies.

5.1 The Barrel and Endcap Hadron Calorimeters

All HB and HE scintillator tiles had their response measured in-situ using either 1.5 or 5 mCiCo60 sources. The averages of the signals in the 17 layers of HB and HE were used to equalizethe response of all HB and HE towers. The absolute energy scale was set using the response to50 GeV/c charged pions of the parts of the detector exposed to the test beam studies.

Table 1: Mean and RMS of the muon energy distributions measured in four regions of HB,before and after correcting the calibration constants using cosmic ray muon data information.

Detector region Mean before RMS before Mean after RMS afterregion correction (GeV) correction (GeV) correction (GeV) correction (GeV)

HB-: iφ 5-32 1.87 ± 0.03 0.12 1.78 ± 0.01 0.05HB-: iφ 39-70 1.83 ± 0.02 0.08 1.75 ± 0.02 0.07HB+: iφ 5-32 1.81 ± 0.02 0.08 1.78 ± 0.01 0.05HB+: iφ 39-70 1.70 ± 0.02 0.09 1.74 ± 0.01 0.04

The cosmic ray muons and splash events were used to check the initial calibration conditions.The results from both methods point to non-uniformities in HB calorimeter response in differ-

5.1 The Barrel and Endcap Hadron Calorimeters 11

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Figure 7: Left: Ratio, for cosmic ray muons, of the average signal amplitudes in the twohalves (+z and −z) of HB, as a function of the φ sector index, iφ, after correcting the aver-age signal for the muon path length and normalizing to the thickness of HB at η = 0. Right:Correlation between cosmic ray muon and splash muon signals, for the ratio of the averagesignal in the two halves of HB. The splash muon signals were corrected for the asymmetry inthe muon flux by comparing the events from the beam arriving from the +z side and the −zside.

ent φ sectors, and to a difference in the energy scale between the two halves of HB. Figure 7 (left)shows the ratio of the muon signal amplitudes in HB for z < 0 and z > 0 for cosmic ray muonevents, RCosmic, as a function of the φ sector index, iφ. While Fig. 7 (right) shows that measure-ments for this ratio based on cosmic ray muons and beam splash events, RSplash, have a 75%correlation. The average ratio deviates from unity by ∼7% with a sector-by-sector spread ofabout 10% (see Table 1). The source of these differences is not understood at this time.

The results from the cosmic ray muons were used to correct the calibration of the various HPDs,with one single parameter applied to all channels contained in a given φ sector of one of the two±z halves of HB. Only muons traversing a single φ sector and less than five η channels wereused in the analysis. About half a million CRAFT muons with momentum below 100 GeV/cremain after the full event selection. Sector 13 of HB, where an HPD was replaced beforeCRAFT, was excluded from these studies. Figure 8 shows the peak value of the distributionof the average energy deposited in HB by cosmic ray muons, averaged over all η values of agiven φ sector for two independent data samples. The plot on the left shows the results forthe data used to determine the corrections, while the plot on the right shows the results afterthe corrections are applied to a smaller but independent data sample. Table 1 presents thecorresponding results for four HB regions. After corrections, the signal spread is smaller andthe differences between the mean values for the four regions of HB is significantly reduced,reflecting the improvement of the HPD intercalibration. The mean muon energy measured inthis analysis is smaller than the one shown in Fig. 2 because only tracks with a momentumbelow 100 GeV/c were used.

Similar studies were performed for HE with a limited number of cosmic ray muon events andall splash events. The ratio of the muon signals for the two endcaps as a function of the φ sector


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Figure 9: Left: Ratio, of the splash muons, of the average signal amplitudes in the two HCALendcaps, −z and +z, as a function of the φ sector index, iφ. Right: Corresponding distributionof the signal ratios.

5.2 The Outer Hadron Calorimeter 13

index is shown in Fig. 9 (right) for splash events. The RSplash mean and the spread of this ratioare shown in Fig. 9 (left). The average is consistent with unity and the spread is smaller than7%. Therefore, no correction to the HE calibration was made.

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Figure 10: Left: Momentum spectrum of the muons selected by this analysis. Right: (top)Energy loss of cosmic ray muons in HB after correcting the signal mean value for the muonpath length and normalizing to the thickness of HB at η = 0; (bottom) ratio of data and MonteCarlo simulation predictions (arbitrary scale) for the bottom half of the calorimeter.

Cosmic ray muons were also used to validate the absolute energy scale and the material de-scription in HB and HE simulations [18]. The absolute energy scale was tested by comparingthe energy loss of muons measured at a test beam and in CRAFT, at a fixed muon momen-tum. From the test beam data it was derived that 150 GeV/c muons deposited 2.80±0.03 GeVin HB [6]. The energy loss measured from CRAFT data, after taking into account the mag-netic field effects and the muon path length, is 2.85 GeV with a statistical error of 0.02 GeV forthe momentum range between 135 and 170 GeV/c. This measurement is in good agreementwith the test beam result. A wide muon momentum range was used to test the simulation.Figure 10 (left) shows the cosmic ray muon energy spectrum measured with the tracker. Fig-ure 10 (right top) shows the muon energy deposited in a calorimeter tower, corrected for thepath length and normalized to the thickness of HB at η = 0, that is, 110 cm. The relativisticrise of the energy loss for muons between 6 and 1000 GeV/c is clearly observed and is consis-tent with expectations [19]. Figure 10 (right bottom) illustrates the consistency of the data andsimulation [18] as a function of the track momentum; the data to simulation ratio shown at anarbitrary scale.

5.2 The Outer Hadron Calorimeter

Since the HO scintillators were not precalibrated with the radioactive source, the calibration ofeach tower was performed using cosmic ray muons from CRUZET, at a uniform high voltagevalue of 8 kV. This calibration agrees well with the measurements performed at a test beam [6].

Figure 11 shows the mean values of the muon signals in HO, given in ADC counts for CRUZETdata. The structure within each ring reflects the differences in signal attenuation caused by thevarying length of the fibers that carry the signals to the photodetectors.


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5.3 The Forward Hadron Calorimeter

The calibration for HF was obtained from measurements with radioactive sources and from testbeam data. Five HF wedges were precalibrated at the test beam with 100 GeV/c electrons [3]and with a 5 mCi Co60 source. Figure 12 displays the good correlation between the signals of theelectrons and the source measurement in the same η, φ sector, separately for short (crosses) andlong (circles) fibers. The average value for the calibration coefficients of the short (long) fibers is0.34 (0.21) GeV/fC. This information was used to set the energy scale for all the channels whichwere not exposed to the beam, using the results of their measurement with the radioactivesource.

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The monitoring of the HF calibration relies on single photoelectron distributions (SPE) mea-

15

suments performed with the LED system. Earlier measurements performed at a test beamshowed that 25 SPEs are equivalent to 100 GeV [3]. The major difference between using theSPE measurements and using a radioactive source is that the SPE characterizes the PMT per-formance alone, while the radioactive source creates Cherenkov light inside the detector whichin turn detected by the PMTs. Therefore, the light collection efficiency and the PMT photocath-ode sensitivity are taken into account in the source calibration, but not in the SPE technique.However, if the attenuation of Cherenkov light as it propagates from the fiber to the PMT isonly affected by small variations from channel to channel, or if the attenuation is negligible,the two calibration techniques should be equivalent.

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A comparison between the results obtained with the radioactive source and new SPE mea-surements, performed after the final HF installation, revealed that 20 of the 1728 channels hadinconsistent calibration, see Fig. 13 (left). The beam splash events confirmed this calibrationproblem since the same channels were found to show an energy response inconsistent withtheir neighbors. Therefore, for those channels the source calibration constants were replacedby the SPE constants.

Figure 13 (right) shows the correlation between the calibration coefficients obtained from singlephotoelectron distributions and the coefficients obtained from the radioactive source calibra-tion, after correcting the few outliers mentioned above.

6 Summary

The performance of the CMS hadron calorimeter has been studied using cosmic ray and beamsplash events, providing improved calibrations with respect to those obtained in test beam dataand with radioactive sources.

As a result of this calibration effort, the barrel portion is intercalibrated to the level of 5%, for85% of the channels. The other HCAL portions have all their channels intercalibrated to betterthan 10% (HE), 12% (HF) and 5% (HO). Furthermore, the presence of the magnetic field results

16 6 Summary

in a measured increase of the signal, by 9.4% in HB and 8% in HE, as expected.

Noise studies have been performed, showing that noise will contribute a trigger rate of around100 Hz. This rate is stable.

In conclusion, the CRAFT data and the beam splash events from 2008 provided an improvedcalibration of the HCAL. This subdetector is now ready for LHC collisions.

Acknowledgments

We thank the technical and administrative staff at CERN and other CMS Institutes, and ac-knowledge support from: FMSR (Austria); FNRS and FWO (Belgium); CNPq, CAPES, FAPERJ,and FAPESP (Brazil); MES (Bulgaria); CERN; CAS, MoST, and NSFC (China); COLCIEN-CIAS (Colombia); MSES (Croatia); RPF (Cyprus); Academy of Sciences and NICPB (Estonia);Academy of Finland, ME, and HIP (Finland); CEA and CNRS/IN2P3 (France); BMBF, DFG,and HGF (Germany); GSRT (Greece); OTKA and NKTH (Hungary); DAE and DST (India);IPM (Iran); SFI (Ireland); INFN (Italy); NRF (Korea); LAS (Lithuania); CINVESTAV, CONA-CYT, SEP, and UASLP-FAI (Mexico); PAEC (Pakistan); SCSR (Poland); FCT (Portugal); JINR(Armenia, Belarus, Georgia, Ukraine, Uzbekistan); MST and MAE (Russia); MSTDS (Serbia);MICINN and CPAN (Spain); Swiss Funding Agencies (Switzerland); NSC (Taipei); TUBITAKand TAEK (Turkey); STFC (United Kingdom); DOE and NSF (USA). Individuals have receivedsupport from the Marie-Curie IEF program (European Union); the Leventis Foundation; the A.P. Sloan Foundation; and the Alexander von Humboldt Foundation.

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18 6 Summary

19

A The CMS Collaboration

Yerevan Physics Institute, Yerevan, ArmeniaS. Chatrchyan, V. Khachatryan, A.M. Sirunyan

Institut für Hochenergiephysik der OeAW, Wien, AustriaW. Adam, B. Arnold, H. Bergauer, T. Bergauer, M. Dragicevic, M. Eichberger, J. Erö, M. Friedl,R. Frühwirth, V.M. Ghete, J. Hammer1, S. Hänsel, M. Hoch, N. Hörmann, J. Hrubec, M. Jeitler,G. Kasieczka, K. Kastner, M. Krammer, D. Liko, I. Magrans de Abril, I. Mikulec, F. Mittermayr,B. Neuherz, M. Oberegger, M. Padrta, M. Pernicka, H. Rohringer, S. Schmid, R. Schöfbeck,T. Schreiner, R. Stark, H. Steininger, J. Strauss, A. Taurok, F. Teischinger, T. Themel, D. Uhl,P. Wagner, W. Waltenberger, G. Walzel, E. Widl, C.-E. Wulz

National Centre for Particle and High Energy Physics, Minsk, BelarusV. Chekhovsky, O. Dvornikov, I. Emeliantchik, A. Litomin, V. Makarenko, I. Marfin,V. Mossolov, N. Shumeiko, A. Solin, R. Stefanovitch, J. Suarez Gonzalez, A. Tikhonov

Research Institute for Nuclear Problems, Minsk, BelarusA. Fedorov, A. Karneyeu, M. Korzhik, V. Panov, R. Zuyeuski

Research Institute of Applied Physical Problems, Minsk, BelarusP. Kuchinsky

Universiteit Antwerpen, Antwerpen, BelgiumW. Beaumont, L. Benucci, M. Cardaci, E.A. De Wolf, E. Delmeire, D. Druzhkin, M. Hashemi,X. Janssen, T. Maes, L. Mucibello, S. Ochesanu, R. Rougny, M. Selvaggi, H. Van Haevermaet,P. Van Mechelen, N. Van Remortel

Vrije Universiteit Brussel, Brussel, BelgiumV. Adler, S. Beauceron, S. Blyweert, J. D’Hondt, S. De Weirdt, O. Devroede, J. Heyninck, A. Ka-logeropoulos, J. Maes, M. Maes, M.U. Mozer, S. Tavernier, W. Van Doninck1, P. Van Mulders,I. Villella

Université Libre de Bruxelles, Bruxelles, BelgiumO. Bouhali, E.C. Chabert, O. Charaf, B. Clerbaux, G. De Lentdecker, V. Dero, S. Elgammal,A.P.R. Gay, G.H. Hammad, P.E. Marage, S. Rugovac, C. Vander Velde, P. Vanlaer, J. Wickens

Ghent University, Ghent, BelgiumM. Grunewald, B. Klein, A. Marinov, D. Ryckbosch, F. Thyssen, M. Tytgat, L. Vanelderen,P. Verwilligen

Université Catholique de Louvain, Louvain-la-Neuve, BelgiumS. Basegmez, G. Bruno, J. Caudron, C. Delaere, P. Demin, D. Favart, A. Giammanco,G. Grégoire, V. Lemaitre, O. Militaru, S. Ovyn, K. Piotrzkowski1, L. Quertenmont, N. Schul

Université de Mons, Mons, BelgiumN. Beliy, E. Daubie

Centro Brasileiro de Pesquisas Fisicas, Rio de Janeiro, BrazilG.A. Alves, M.E. Pol, M.H.G. Souza

Universidade do Estado do Rio de Janeiro, Rio de Janeiro, BrazilW. Carvalho, D. De Jesus Damiao, C. De Oliveira Martins, S. Fonseca De Souza, L. Mundim,V. Oguri, A. Santoro, S.M. Silva Do Amaral, A. Sznajder

Instituto de Fisica Teorica, Universidade Estadual Paulista, Sao Paulo, Brazil

20 A The CMS Collaboration

T.R. Fernandez Perez Tomei, M.A. Ferreira Dias, E. M. Gregores2, S.F. Novaes

Institute for Nuclear Research and Nuclear Energy, Sofia, BulgariaK. Abadjiev1, T. Anguelov, J. Damgov, N. Darmenov1, L. Dimitrov, V. Genchev1, P. Iaydjiev,S. Piperov, S. Stoykova, G. Sultanov, R. Trayanov, I. Vankov

University of Sofia, Sofia, BulgariaA. Dimitrov, M. Dyulendarova, V. Kozhuharov, L. Litov, E. Marinova, M. Mateev, B. Pavlov,P. Petkov, Z. Toteva1

Institute of High Energy Physics, Beijing, ChinaG.M. Chen, H.S. Chen, W. Guan, C.H. Jiang, D. Liang, B. Liu, X. Meng, J. Tao, J. Wang, Z. Wang,Z. Xue, Z. Zhang

State Key Lab. of Nucl. Phys. and Tech., Peking University, Beijing, ChinaY. Ban, J. Cai, Y. Ge, S. Guo, Z. Hu, Y. Mao, S.J. Qian, H. Teng, B. Zhu

Universidad de Los Andes, Bogota, ColombiaC. Avila, M. Baquero Ruiz, C.A. Carrillo Montoya, A. Gomez, B. Gomez Moreno, A.A. OcampoRios, A.F. Osorio Oliveros, D. Reyes Romero, J.C. Sanabria

Technical University of Split, Split, CroatiaN. Godinovic, K. Lelas, R. Plestina, D. Polic, I. Puljak

University of Split, Split, CroatiaZ. Antunovic, M. Dzelalija

Institute Rudjer Boskovic, Zagreb, CroatiaV. Brigljevic, S. Duric, K. Kadija, S. Morovic

University of Cyprus, Nicosia, CyprusR. Fereos, M. Galanti, J. Mousa, A. Papadakis, F. Ptochos, P.A. Razis, D. Tsiakkouri, Z. Zinonos

National Institute of Chemical Physics and Biophysics, Tallinn, EstoniaA. Hektor, M. Kadastik, K. Kannike, M. Müntel, M. Raidal, L. Rebane

Helsinki Institute of Physics, Helsinki, FinlandE. Anttila, S. Czellar, J. Härkönen, A. Heikkinen, V. Karimäki, R. Kinnunen, J. Klem, M.J. Ko-rtelainen, T. Lampén, K. Lassila-Perini, S. Lehti, T. Lindén, P. Luukka, T. Mäenpää, J. Nysten,E. Tuominen, J. Tuominiemi, D. Ungaro, L. Wendland

Lappeenranta University of Technology, Lappeenranta, FinlandK. Banzuzi, A. Korpela, T. Tuuva

Laboratoire d’Annecy-le-Vieux de Physique des Particules, IN2P3-CNRS, Annecy-le-Vieux,FranceP. Nedelec, D. Sillou

DSM/IRFU, CEA/Saclay, Gif-sur-Yvette, FranceM. Besancon, R. Chipaux, M. Dejardin, D. Denegri, J. Descamps, B. Fabbro, J.L. Faure, F. Ferri,S. Ganjour, F.X. Gentit, A. Givernaud, P. Gras, G. Hamel de Monchenault, P. Jarry, M.C. Lemaire,E. Locci, J. Malcles, M. Marionneau, L. Millischer, J. Rander, A. Rosowsky, D. Rousseau,M. Titov, P. Verrecchia

Laboratoire Leprince-Ringuet, Ecole Polytechnique, IN2P3-CNRS, Palaiseau, FranceS. Baffioni, L. Bianchini, M. Bluj3, P. Busson, C. Charlot, L. Dobrzynski, R. Granier de Cas-sagnac, M. Haguenauer, P. Miné, P. Paganini, Y. Sirois, C. Thiebaux, A. Zabi

21

Institut Pluridisciplinaire Hubert Curien, Université de Strasbourg, Université de HauteAlsace Mulhouse, CNRS/IN2P3, Strasbourg, FranceJ.-L. Agram4, A. Besson, D. Bloch, D. Bodin, J.-M. Brom, E. Conte4, F. Drouhin4, J.-C. Fontaine4,D. Gelé, U. Goerlach, L. Gross, P. Juillot, A.-C. Le Bihan, Y. Patois, J. Speck, P. Van Hove

Université de Lyon, Université Claude Bernard Lyon 1, CNRS-IN2P3, Institut de PhysiqueNucléaire de Lyon, Villeurbanne, FranceC. Baty, M. Bedjidian, J. Blaha, G. Boudoul, H. Brun, N. Chanon, R. Chierici, D. Contardo,P. Depasse, T. Dupasquier, H. El Mamouni, F. Fassi5, J. Fay, S. Gascon, B. Ille, T. Kurca, T. LeGrand, M. Lethuillier, N. Lumb, L. Mirabito, S. Perries, M. Vander Donckt, P. Verdier

E. Andronikashvili Institute of Physics, Academy of Science, Tbilisi, GeorgiaN. Djaoshvili, N. Roinishvili, V. Roinishvili

Institute of High Energy Physics and Informatization, Tbilisi State University, Tbilisi,GeorgiaN. Amaglobeli

RWTH Aachen University, I. Physikalisches Institut, Aachen, GermanyR. Adolphi, G. Anagnostou, R. Brauer, W. Braunschweig, M. Edelhoff, H. Esser, L. Feld,W. Karpinski, A. Khomich, K. Klein, N. Mohr, A. Ostaptchouk, D. Pandoulas, G. Pierschel,F. Raupach, S. Schael, A. Schultz von Dratzig, G. Schwering, D. Sprenger, M. Thomas, M. Weber,B. Wittmer, M. Wlochal

RWTH Aachen University, III. Physikalisches Institut A, Aachen, GermanyO. Actis, G. Altenhöfer, W. Bender, P. Biallass, M. Erdmann, G. Fetchenhauer1, J. Frangenheim,T. Hebbeker, G. Hilgers, A. Hinzmann, K. Hoepfner, C. Hof, M. Kirsch, T. Klimkovich,P. Kreuzer1, D. Lanske†, M. Merschmeyer, A. Meyer, B. Philipps, H. Pieta, H. Reithler,S.A. Schmitz, L. Sonnenschein, M. Sowa, J. Steggemann, H. Szczesny, D. Teyssier, C. Zeidler

RWTH Aachen University, III. Physikalisches Institut B, Aachen, GermanyM. Bontenackels, M. Davids, M. Duda, G. Flügge, H. Geenen, M. Giffels, W. Haj Ahmad, T. Her-manns, D. Heydhausen, S. Kalinin, T. Kress, A. Linn, A. Nowack, L. Perchalla, M. Poettgens,O. Pooth, P. Sauerland, A. Stahl, D. Tornier, M.H. Zoeller

Deutsches Elektronen-Synchrotron, Hamburg, GermanyM. Aldaya Martin, U. Behrens, K. Borras, A. Campbell, E. Castro, D. Dammann, G. Eckerlin,A. Flossdorf, G. Flucke, A. Geiser, D. Hatton, J. Hauk, H. Jung, M. Kasemann, I. Katkov,C. Kleinwort, H. Kluge, A. Knutsson, E. Kuznetsova, W. Lange, W. Lohmann, R. Mankel1,M. Marienfeld, A.B. Meyer, S. Miglioranzi, J. Mnich, M. Ohlerich, J. Olzem, A. Parenti,C. Rosemann, R. Schmidt, T. Schoerner-Sadenius, D. Volyanskyy, C. Wissing, W.D. Zeuner1

University of Hamburg, Hamburg, GermanyC. Autermann, F. Bechtel, J. Draeger, D. Eckstein, U. Gebbert, K. Kaschube, G. Kaussen,R. Klanner, B. Mura, S. Naumann-Emme, F. Nowak, U. Pein, C. Sander, P. Schleper, T. Schum,H. Stadie, G. Steinbrück, J. Thomsen, R. Wolf

Institut für Experimentelle Kernphysik, Karlsruhe, GermanyJ. Bauer, P. Blüm, V. Buege, A. Cakir, T. Chwalek, W. De Boer, A. Dierlamm, G. Dirkes,M. Feindt, U. Felzmann, M. Frey, A. Furgeri, J. Gruschke, C. Hackstein, F. Hartmann1,S. Heier, M. Heinrich, H. Held, D. Hirschbuehl, K.H. Hoffmann, S. Honc, C. Jung, T. Kuhr,T. Liamsuwan, D. Martschei, S. Mueller, Th. Müller, M.B. Neuland, M. Niegel, O. Oberst,A. Oehler, J. Ott, T. Peiffer, D. Piparo, G. Quast, K. Rabbertz, F. Ratnikov, N. Ratnikova, M. Renz,C. Saout1, G. Sartisohn, A. Scheurer, P. Schieferdecker, F.-P. Schilling, G. Schott, H.J. Simonis,


F.M. Stober, P. Sturm, D. Troendle, A. Trunov, W. Wagner, J. Wagner-Kuhr, M. Zeise, V. Zhukov6,E.B. Ziebarth

Institute of Nuclear Physics ”Demokritos”, Aghia Paraskevi, GreeceG. Daskalakis, T. Geralis, K. Karafasoulis, A. Kyriakis, D. Loukas, A. Markou, C. Markou,C. Mavrommatis, E. Petrakou, A. Zachariadou

University of Athens, Athens, GreeceL. Gouskos, P. Katsas, A. Panagiotou1

University of Ioánnina, Ioánnina, GreeceI. Evangelou, P. Kokkas, N. Manthos, I. Papadopoulos, V. Patras, F.A. Triantis

KFKI Research Institute for Particle and Nuclear Physics, Budapest, HungaryG. Bencze1, L. Boldizsar, G. Debreczeni, C. Hajdu1, S. Hernath, P. Hidas, D. Horvath7, K. Kra-jczar, A. Laszlo, G. Patay, F. Sikler, N. Toth, G. Vesztergombi

Institute of Nuclear Research ATOMKI, Debrecen, HungaryN. Beni, G. Christian, J. Imrek, J. Molnar, D. Novak, J. Palinkas, G. Szekely, Z. Szillasi1,K. Tokesi, V. Veszpremi

University of Debrecen, Debrecen, HungaryA. Kapusi, G. Marian, P. Raics, Z. Szabo, Z.L. Trocsanyi, B. Ujvari, G. Zilizi

Panjab University, Chandigarh, IndiaS. Bansal, H.S. Bawa, S.B. Beri, V. Bhatnagar, M. Jindal, M. Kaur, R. Kaur, J.M. Kohli,M.Z. Mehta, N. Nishu, L.K. Saini, A. Sharma, A. Singh, J.B. Singh, S.P. Singh

University of Delhi, Delhi, IndiaS. Ahuja, S. Arora, S. Bhattacharya8, S. Chauhan, B.C. Choudhary, P. Gupta, S. Jain, S. Jain,M. Jha, A. Kumar, K. Ranjan, R.K. Shivpuri, A.K. Srivastava

Bhabha Atomic Research Centre, Mumbai, IndiaR.K. Choudhury, D. Dutta, S. Kailas, S.K. Kataria, A.K. Mohanty, L.M. Pant, P. Shukla, A. Top-kar

Tata Institute of Fundamental Research - EHEP, Mumbai, IndiaT. Aziz, M. Guchait9, A. Gurtu, M. Maity10, D. Majumder, G. Majumder, K. Mazumdar,A. Nayak, A. Saha, K. Sudhakar

Tata Institute of Fundamental Research - HECR, Mumbai, IndiaS. Banerjee, S. Dugad, N.K. Mondal

Institute for Studies in Theoretical Physics & Mathematics (IPM), Tehran, IranH. Arfaei, H. Bakhshiansohi, A. Fahim, A. Jafari, M. Mohammadi Najafabadi, A. Moshaii,S. Paktinat Mehdiabadi, S. Rouhani, B. Safarzadeh, M. Zeinali

University College Dublin, Dublin, IrelandM. Felcini

INFN Sezione di Bari a, Università di Bari b, Politecnico di Bari c, Bari, ItalyM. Abbresciaa ,b, L. Barbonea, F. Chiumaruloa, A. Clementea, A. Colaleoa, D. Creanzaa,c,G. Cuscelaa, N. De Filippisa, M. De Palmaa,b, G. De Robertisa, G. Donvitoa, F. Fedelea, L. Fiorea,M. Francoa, G. Iasellia,c, N. Lacalamitaa, F. Loddoa, L. Lusitoa,b, G. Maggia,c, M. Maggia,N. Mannaa,b, B. Marangellia ,b, S. Mya ,c, S. Natalia ,b, S. Nuzzoa,b, G. Papagnia, S. Piccolomoa,G.A. Pierroa, C. Pintoa, A. Pompilia ,b, G. Pugliesea ,c, R. Rajana, A. Ranieria, F. Romanoa,c,

23

G. Rosellia,b, G. Selvaggia ,b, Y. Shindea, L. Silvestrisa, S. Tupputia ,b, G. Zitoa

INFN Sezione di Bologna a, Universita di Bologna b, Bologna, ItalyG. Abbiendia, W. Bacchia ,b, A.C. Benvenutia, M. Boldinia, D. Bonacorsia, S. Braibant-Giacomellia,b, V.D. Cafaroa, S.S. Caiazzaa, P. Capiluppia,b, A. Castroa ,b, F.R. Cavalloa,G. Codispotia,b, M. Cuffiania,b, I. D’Antonea, G.M. Dallavallea,1, F. Fabbria, A. Fanfania ,b,D. Fasanellaa, P. Giacomellia, V. Giordanoa, M. Giuntaa ,1, C. Grandia, M. Guerzonia,S. Marcellinia, G. Masettia,b, A. Montanaria, F.L. Navarriaa,b, F. Odoricia, G. Pellegrinia,A. Perrottaa, A.M. Rossia,b, T. Rovellia ,b, G. Sirolia ,b, G. Torromeoa, R. Travaglinia ,b

INFN Sezione di Catania a, Universita di Catania b, Catania, ItalyS. Albergoa,b, S. Costaa,b, R. Potenzaa,b, A. Tricomia,b, C. Tuvea

INFN Sezione di Firenze a, Universita di Firenze b, Firenze, ItalyG. Barbaglia, G. Broccoloa,b, V. Ciullia ,b, C. Civininia, R. D’Alessandroa ,b, E. Focardia ,b,S. Frosalia,b, E. Galloa, C. Gentaa,b, G. Landia ,b, P. Lenzia,b,1, M. Meschinia, S. Paolettia,G. Sguazzonia, A. Tropianoa

INFN Laboratori Nazionali di Frascati, Frascati, ItalyL. Benussi, M. Bertani, S. Bianco, S. Colafranceschi11, D. Colonna11, F. Fabbri, M. Giardoni,L. Passamonti, D. Piccolo, D. Pierluigi, B. Ponzio, A. Russo

INFN Sezione di Genova, Genova, ItalyP. Fabbricatore, R. Musenich

INFN Sezione di Milano-Biccoca a, Universita di Milano-Bicocca b, Milano, ItalyA. Benagliaa, M. Callonia, G.B. Ceratia ,b,1, P. D’Angeloa, F. De Guioa, F.M. Farinaa, A. Ghezzia,P. Govonia,b, M. Malbertia,b,1, S. Malvezzia, A. Martellia, D. Menascea, V. Miccioa,b, L. Moronia,P. Negria,b, M. Paganonia ,b, D. Pedrinia, A. Pulliaa ,b, S. Ragazzia ,b, N. Redaellia, S. Salaa,R. Salernoa,b, T. Tabarelli de Fatisa ,b, V. Tancinia,b, S. Taronia ,b

INFN Sezione di Napoli a, Universita di Napoli ”Federico II” b, Napoli, ItalyS. Buontempoa, N. Cavalloa, A. Cimminoa ,b,1, M. De Gruttolaa,b,1, F. Fabozzia,12, A.O.M. Iorioa,L. Listaa, D. Lomidzea, P. Nolia ,b, P. Paoluccia, C. Sciaccaa,b

INFN Sezione di Padova a, Università di Padova b, Padova, ItalyP. Azzia,1, N. Bacchettaa, L. Barcellana, P. Bellana ,b,1, M. Bellatoa, M. Benettonia, M. Biasottoa ,13,D. Biselloa,b, E. Borsatoa ,b, A. Brancaa, R. Carlina ,b, L. Castellania, P. Checchiaa, E. Contia,F. Dal Corsoa, M. De Mattiaa,b, T. Dorigoa, U. Dossellia, F. Fanzagoa, F. Gasparinia ,b,U. Gasparinia,b, P. Giubilatoa,b, F. Gonellaa, A. Greselea,14, M. Gulminia ,13, A. Kaminskiya ,b,S. Lacapraraa ,13, I. Lazzizzeraa ,14, M. Margonia ,b, G. Marona ,13, S. Mattiazzoa,b, M. Mazzucatoa,M. Meneghellia, A.T. Meneguzzoa,b, M. Michelottoa, F. Montecassianoa, M. Nespoloa,M. Passaseoa, M. Pegoraroa, L. Perrozzia, N. Pozzobona ,b, P. Ronchesea,b, F. Simonettoa,b,N. Tonioloa, E. Torassaa, M. Tosia ,b, A. Triossia, S. Vaninia ,b, S. Venturaa, P. Zottoa,b,G. Zumerlea,b

INFN Sezione di Pavia a, Universita di Pavia b, Pavia, ItalyP. Baessoa,b, U. Berzanoa, S. Bricolaa, M.M. Necchia ,b, D. Paganoa,b, S.P. Rattia,b, C. Riccardia,b,P. Torrea ,b, A. Vicinia, P. Vituloa,b, C. Viviania,b

INFN Sezione di Perugia a, Universita di Perugia b, Perugia, ItalyD. Aisaa, S. Aisaa, E. Babuccia, M. Biasinia,b, G.M. Bileia, B. Caponeria,b, B. Checcuccia, N. Dinua,L. Fanòa, L. Farnesinia, P. Laricciaa,b, A. Lucaronia,b, G. Mantovania ,b, A. Nappia,b, A. Pilusoa,V. Postolachea, A. Santocchiaa,b, L. Servolia, D. Tonoiua, A. Vedaeea, R. Volpea ,b


INFN Sezione di Pisa a, Universita di Pisa b, Scuola Normale Superiore di Pisa c, Pisa, ItalyP. Azzurria ,c, G. Bagliesia, J. Bernardinia,b, L. Berrettaa, T. Boccalia, A. Boccia ,c, L. Borrelloa,c,F. Bosia, F. Calzolaria, R. Castaldia, R. Dell’Orsoa, F. Fioria,b, L. Foàa ,c, S. Gennaia,c, A. Giassia,A. Kraana, F. Ligabuea ,c, T. Lomtadzea, F. Mariania, L. Martinia, M. Massaa, A. Messineoa ,b,A. Moggia, F. Pallaa, F. Palmonaria, G. Petragnania, G. Petrucciania ,c, F. Raffaellia, S. Sarkara,G. Segneria, A.T. Serbana, P. Spagnoloa ,1, R. Tenchinia ,1, S. Tolainia, G. Tonellia,b,1, A. Venturia,P.G. Verdinia

INFN Sezione di Roma a, Universita di Roma ”La Sapienza” b, Roma, ItalyS. Baccaroa ,15, L. Baronea,b, A. Bartolonia, F. Cavallaria ,1, I. Dafineia, D. Del Rea ,b, E. DiMarcoa ,b, M. Diemoza, D. Francia,b, E. Longoa,b, G. Organtinia ,b, A. Palmaa ,b, F. Pandolfia ,b,R. Paramattia,1, F. Pellegrinoa, S. Rahatloua ,b, C. Rovellia

INFN Sezione di Torino a, Università di Torino b, Università del Piemonte Orientale (No-vara) c, Torino, ItalyG. Alampia, N. Amapanea ,b, R. Arcidiaconoa,b, S. Argiroa,b, M. Arneodoa ,c, C. Biinoa,M.A. Borgiaa,b, C. Bottaa,b, N. Cartigliaa, R. Castelloa ,b, G. Cerminaraa,b, M. Costaa ,b,D. Dattolaa, G. Dellacasaa, N. Demariaa, G. Dugheraa, F. Dumitrachea, A. Grazianoa ,b,C. Mariottia, M. Maronea,b, S. Masellia, E. Migliorea,b, G. Milaa ,b, V. Monacoa ,b, M. Musicha ,b,M. Nervoa ,b, M.M. Obertinoa ,c, S. Oggeroa,b, R. Paneroa, N. Pastronea, M. Pelliccionia ,b,A. Romeroa,b, M. Ruspaa,c, R. Sacchia,b, A. Solanoa,b, A. Staianoa, P.P. Trapania ,b ,1, D. Trocinoa ,b,A. Vilela Pereiraa,b, L. Viscaa,b, A. Zampieria

INFN Sezione di Trieste a, Universita di Trieste b, Trieste, ItalyF. Ambroglinia ,b, S. Belfortea, F. Cossuttia, G. Della Riccaa,b, B. Gobboa, A. Penzoa

Kyungpook National University, Daegu, KoreaS. Chang, J. Chung, D.H. Kim, G.N. Kim, D.J. Kong, H. Park, D.C. Son

Wonkwang University, Iksan, KoreaS.Y. Bahk

Chonnam National University, Kwangju, KoreaS. Song

Konkuk University, Seoul, KoreaS.Y. Jung

Korea University, Seoul, KoreaB. Hong, H. Kim, J.H. Kim, K.S. Lee, D.H. Moon, S.K. Park, H.B. Rhee, K.S. Sim

Seoul National University, Seoul, KoreaJ. Kim

University of Seoul, Seoul, KoreaM. Choi, G. Hahn, I.C. Park

Sungkyunkwan University, Suwon, KoreaS. Choi, Y. Choi, J. Goh, H. Jeong, T.J. Kim, J. Lee, S. Lee

Vilnius University, Vilnius, LithuaniaM. Janulis, D. Martisiute, P. Petrov, T. Sabonis

Centro de Investigacion y de Estudios Avanzados del IPN, Mexico City, MexicoH. Castilla Valdez1, A. Sánchez Hernández

25

Universidad Iberoamericana, Mexico City, MexicoS. Carrillo Moreno

Universidad Autónoma de San Luis Potosı́, San Luis Potosı́, MexicoA. Morelos Pineda

University of Auckland, Auckland, New ZealandP. Allfrey, R.N.C. Gray, D. Krofcheck

University of Canterbury, Christchurch, New ZealandN. Bernardino Rodrigues, P.H. Butler, T. Signal, J.C. Williams

National Centre for Physics, Quaid-I-Azam University, Islamabad, PakistanM. Ahmad, I. Ahmed, W. Ahmed, M.I. Asghar, M.I.M. Awan, H.R. Hoorani, I. Hussain,W.A. Khan, T. Khurshid, S. Muhammad, S. Qazi, H. Shahzad

Institute of Experimental Physics, Warsaw, PolandM. Cwiok, R. Dabrowski, W. Dominik, K. Doroba, M. Konecki, J. Krolikowski, K. Pozniak16,R. Romaniuk, W. Zabolotny16, P. Zych

Soltan Institute for Nuclear Studies, Warsaw, PolandT. Frueboes, R. Gokieli, L. Goscilo, M. Górski, M. Kazana, K. Nawrocki, M. Szleper, G. Wrochna,P. Zalewski

Laboratório de Instrumentação e Fı́sica Experimental de Partı́culas, Lisboa, PortugalN. Almeida, L. Antunes Pedro, P. Bargassa, A. David, P. Faccioli, P.G. Ferreira Parracho,M. Freitas Ferreira, M. Gallinaro, M. Guerra Jordao, P. Martins, G. Mini, P. Musella, J. Pela,L. Raposo, P.Q. Ribeiro, S. Sampaio, J. Seixas, J. Silva, P. Silva, D. Soares, M. Sousa, J. Varela,H.K. Wöhri

Joint Institute for Nuclear Research, Dubna, RussiaI. Altsybeev, I. Belotelov, P. Bunin, Y. Ershov, I. Filozova, M. Finger, M. Finger Jr., A. Golunov,I. Golutvin, N. Gorbounov, V. Kalagin, A. Kamenev, V. Karjavin, V. Konoplyanikov, V. Ko-renkov, G. Kozlov, A. Kurenkov, A. Lanev, A. Makankin, V.V. Mitsyn, P. Moisenz, E. Nikonov,D. Oleynik, V. Palichik, V. Perelygin, A. Petrosyan, R. Semenov, S. Shmatov, V. Smirnov,D. Smolin, E. Tikhonenko, S. Vasil’ev, A. Vishnevskiy, A. Volodko, A. Zarubin, V. Zhiltsov

Petersburg Nuclear Physics Institute, Gatchina (St Petersburg), RussiaN. Bondar, L. Chtchipounov, A. Denisov, Y. Gavrikov, G. Gavrilov, V. Golovtsov, Y. Ivanov,V. Kim, V. Kozlov, P. Levchenko, G. Obrant, E. Orishchin, A. Petrunin, Y. Shcheglov, A. Shchet-kovskiy, V. Sknar, I. Smirnov, V. Sulimov, V. Tarakanov, L. Uvarov, S. Vavilov, G. Velichko,S. Volkov, A. Vorobyev

Institute for Nuclear Research, Moscow, RussiaYu. Andreev, A. Anisimov, P. Antipov, A. Dermenev, S. Gninenko, N. Golubev, M. Kirsanov,N. Krasnikov, V. Matveev, A. Pashenkov, V.E. Postoev, A. Solovey, A. Solovey, A. Toropin,S. Troitsky

Institute for Theoretical and Experimental Physics, Moscow, RussiaA. Baud, V. Epshteyn, V. Gavrilov, N. Ilina, V. Kaftanov†, V. Kolosov, M. Kossov1, A. Krokhotin,S. Kuleshov, A. Oulianov, G. Safronov, S. Semenov, I. Shreyber, V. Stolin, E. Vlasov, A. Zhokin

Moscow State University, Moscow, RussiaE. Boos, M. Dubinin17, L. Dudko, A. Ershov, A. Gribushin, V. Klyukhin, O. Kodolova, I. Lokhtin,S. Petrushanko, L. Sarycheva, V. Savrin, A. Snigirev, I. Vardanyan


P.N. Lebedev Physical Institute, Moscow, RussiaI. Dremin, M. Kirakosyan, N. Konovalova, S.V. Rusakov, A. Vinogradov

State Research Center of Russian Federation, Institute for High Energy Physics, Protvino,RussiaS. Akimenko, A. Artamonov, I. Azhgirey, S. Bitioukov, V. Burtovoy, V. Grishin1, V. Kachanov,D. Konstantinov, V. Krychkine, A. Levine, I. Lobov, V. Lukanin, Y. Mel’nik, V. Petrov, R. Ryutin,S. Slabospitsky, A. Sobol, A. Sytine, L. Tourtchanovitch, S. Troshin, N. Tyurin, A. Uzunian,A. Volkov

Vinca Institute of Nuclear Sciences, Belgrade, SerbiaP. Adzic, M. Djordjevic, D. Jovanovic18, D. Krpic18, D. Maletic, J. Puzovic18, N. Smiljkovic

Centro de Investigaciones Energéticas Medioambientales y Tecnológicas (CIEMAT),Madrid, SpainM. Aguilar-Benitez, J. Alberdi, J. Alcaraz Maestre, P. Arce, J.M. Barcala, C. Battilana, C. BurgosLazaro, J. Caballero Bejar, E. Calvo, M. Cardenas Montes, M. Cepeda, M. Cerrada, M. ChamizoLlatas, F. Clemente, N. Colino, M. Daniel, B. De La Cruz, A. Delgado Peris, C. Diez Pardos,C. Fernandez Bedoya, J.P. Fernández Ramos, A. Ferrando, J. Flix, M.C. Fouz, P. Garcia-Abia,A.C. Garcia-Bonilla, O. Gonzalez Lopez, S. Goy Lopez, J.M. Hernandez, M.I. Josa, J. Marin,G. Merino, J. Molina, A. Molinero, J.J. Navarrete, J.C. Oller, J. Puerta Pelayo, L. Romero,J. Santaolalla, C. Villanueva Munoz, C. Willmott, C. Yuste

Universidad Autónoma de Madrid, Madrid, SpainC. Albajar, M. Blanco Otano, J.F. de Trocóniz, A. Garcia Raboso, J.O. Lopez Berengueres

Universidad de Oviedo, Oviedo, SpainJ. Cuevas, J. Fernandez Menendez, I. Gonzalez Caballero, L. Lloret Iglesias, H. Naves Sordo,J.M. Vizan Garcia

Instituto de Fı́sica de Cantabria (IFCA), CSIC-Universidad de Cantabria, Santander, SpainI.J. Cabrillo, A. Calderon, S.H. Chuang, I. Diaz Merino, C. Diez Gonzalez, J. Duarte Campder-ros, M. Fernandez, G. Gomez, J. Gonzalez Sanchez, R. Gonzalez Suarez, C. Jorda, P. LobellePardo, A. Lopez Virto, J. Marco, R. Marco, C. Martinez Rivero, P. Martinez Ruiz del Arbol,F. Matorras, T. Rodrigo, A. Ruiz Jimeno, L. Scodellaro, M. Sobron Sanudo, I. Vila, R. VilarCortabitarte

CERN, European Organization for Nuclear Research, Geneva, SwitzerlandD. Abbaneo, E. Albert, M. Alidra, S. Ashby, E. Auffray, J. Baechler, P. Baillon, A.H. Ball,S.L. Bally, D. Barney, F. Beaudette19, R. Bellan, D. Benedetti, G. Benelli, C. Bernet, P. Bloch,S. Bolognesi, M. Bona, J. Bos, N. Bourgeois, T. Bourrel, H. Breuker, K. Bunkowski, D. Campi,T. Camporesi, E. Cano, A. Cattai, J.P. Chatelain, M. Chauvey, T. Christiansen, J.A. CoarasaPerez, A. Conde Garcia, R. Covarelli, B. Curé, A. De Roeck, V. Delachenal, D. Deyrail, S. DiVincenzo20, S. Dos Santos, T. Dupont, L.M. Edera, A. Elliott-Peisert, M. Eppard, M. Favre,N. Frank, W. Funk, A. Gaddi, M. Gastal, M. Gateau, H. Gerwig, D. Gigi, K. Gill, D. Giordano,J.P. Girod, F. Glege, R. Gomez-Reino Garrido, R. Goudard, S. Gowdy, R. Guida, L. Guiducci,J. Gutleber, M. Hansen, C. Hartl, J. Harvey, B. Hegner, H.F. Hoffmann, A. Holzner, A. Honma,M. Huhtinen, V. Innocente, P. Janot, G. Le Godec, P. Lecoq, C. Leonidopoulos, R. Loos,C. Lourenço, A. Lyonnet, A. Macpherson, N. Magini, J.D. Maillefaud, G. Maire, T. Mäki,L. Malgeri, M. Mannelli, L. Masetti, F. Meijers, P. Meridiani, S. Mersi, E. Meschi, A. MeynetCordonnier, R. Moser, M. Mulders, J. Mulon, M. Noy, A. Oh, G. Olesen, A. Onnela, T. Orimoto,L. Orsini, E. Perez, G. Perinic, J.F. Pernot, P. Petagna, P. Petiot, A. Petrilli, A. Pfeiffer, M. Pierini,M. Pimiä, R. Pintus, B. Pirollet, H. Postema, A. Racz, S. Ravat, S.B. Rew, J. Rodrigues Antunes,

27

G. Rolandi21, M. Rovere, V. Ryjov, H. Sakulin, D. Samyn, H. Sauce, C. Schäfer, W.D. Schlatter,M. Schröder, C. Schwick, A. Sciaba, I. Segoni, A. Sharma, N. Siegrist, P. Siegrist, N. Sinanis,T. Sobrier, P. Sphicas22, D. Spiga, M. Spiropulu17, F. Stöckli, P. Traczyk, P. Tropea, J. Troska,A. Tsirou, L. Veillet, G.I. Veres, M. Voutilainen, P. Wertelaers, M. Zanetti

Paul Scherrer Institut, Villigen, SwitzerlandW. Bertl, K. Deiters, W. Erdmann, K. Gabathuler, R. Horisberger, Q. Ingram, H.C. Kaestli,S. König, D. Kotlinski, U. Langenegger, F. Meier, D. Renker, T. Rohe, J. Sibille23,A. Starodumov24

Institute for Particle Physics, ETH Zurich, Zurich, SwitzerlandB. Betev, L. Caminada25, Z. Chen, S. Cittolin, D.R. Da Silva Di Calafiori, S. Dambach25,G. Dissertori, M. Dittmar, C. Eggel25, J. Eugster, G. Faber, K. Freudenreich, C. Grab, A. Hervé,W. Hintz, P. Lecomte, P.D. Luckey, W. Lustermann, C. Marchica25, P. Milenovic26, F. Moort-gat, A. Nardulli, F. Nessi-Tedaldi, L. Pape, F. Pauss, T. Punz, A. Rizzi, F.J. Ronga, L. Sala,A.K. Sanchez, M.-C. Sawley, V. Sordini, B. Stieger, L. Tauscher†, A. Thea, K. Theofilatos,D. Treille, P. Trüb25, M. Weber, L. Wehrli, J. Weng, S. Zelepoukine27

Universität Zürich, Zurich, SwitzerlandC. Amsler, V. Chiochia, S. De Visscher, C. Regenfus, P. Robmann, T. Rommerskirchen,A. Schmidt, D. Tsirigkas, L. Wilke

National Central University, Chung-Li, TaiwanY.H. Chang, E.A. Chen, W.T. Chen, A. Go, C.M. Kuo, S.W. Li, W. Lin

National Taiwan University (NTU), Taipei, TaiwanP. Bartalini, P. Chang, Y. Chao, K.F. Chen, W.-S. Hou, Y. Hsiung, Y.J. Lei, S.W. Lin, R.-S. Lu,J. Schümann, J.G. Shiu, Y.M. Tzeng, K. Ueno, Y. Velikzhanin, C.C. Wang, M. Wang

Cukurova University, Adana, TurkeyA. Adiguzel, A. Ayhan, A. Azman Gokce, M.N. Bakirci, S. Cerci, I. Dumanoglu, E. Eskut,S. Girgis, E. Gurpinar, I. Hos, T. Karaman, T. Karaman, A. Kayis Topaksu, P. Kurt, G. Önengüt,G. Önengüt Gökbulut, K. Ozdemir, S. Ozturk, A. Polatöz, K. Sogut28, B. Tali, H. Topakli,D. Uzun, L.N. Vergili, M. Vergili

Middle East Technical University, Physics Department, Ankara, TurkeyI.V. Akin, T. Aliev, S. Bilmis, M. Deniz, H. Gamsizkan, A.M. Guler, K. Öcalan, M. Serin, R. Sever,U.E. Surat, M. Zeyrek

Bogaziçi University, Department of Physics, Istanbul, TurkeyM. Deliomeroglu, D. Demir29, E. Gülmez, A. Halu, B. Isildak, M. Kaya30, O. Kaya30, S. Ozkoru-cuklu31, N. Sonmez32

National Scientific Center, Kharkov Institute of Physics and Technology, Kharkov, UkraineL. Levchuk, S. Lukyanenko, D. Soroka, S. Zub

University of Bristol, Bristol, United KingdomF. Bostock, J.J. Brooke, T.L. Cheng, D. Cussans, R. Frazier, J. Goldstein, N. Grant,M. Hansen, G.P. Heath, H.F. Heath, C. Hill, B. Huckvale, J. Jackson, C.K. Mackay, S. Metson,D.M. Newbold33, K. Nirunpong, V.J. Smith, J. Velthuis, R. Walton

Rutherford Appleton Laboratory, Didcot, United KingdomK.W. Bell, C. Brew, R.M. Brown, B. Camanzi, D.J.A. Cockerill, J.A. Coughlan, N.I. Geddes,K. Harder, S. Harper, B.W. Kennedy, P. Murray, C.H. Shepherd-Themistocleous, I.R. Tomalin,J.H. Williams†, W.J. Womersley, S.D. Worm


Imperial College, University of London, London, United KingdomR. Bainbridge, G. Ball, J. Ballin, R. Beuselinck, O. Buchmuller, D. Colling, N. Cripps, G. Davies,M. Della Negra, C. Foudas, J. Fulcher, D. Futyan, G. Hall, J. Hays, G. Iles, G. Karapos-toli, B.C. MacEvoy, A.-M. Magnan, J. Marrouche, J. Nash, A. Nikitenko24, A. Papageorgiou,M. Pesaresi, K. Petridis, M. Pioppi34, D.M. Raymond, N. Rompotis, A. Rose, M.J. Ryan,C. Seez, P. Sharp, G. Sidiropoulos1, M. Stettler, M. Stoye, M. Takahashi, A. Tapper, C. Timlin,S. Tourneur, M. Vazquez Acosta, T. Virdee1, S. Wakefield, D. Wardrope, T. Whyntie, M. Wing-ham

Brunel University, Uxbridge, United KingdomJ.E. Cole, I. Goitom, P.R. Hobson, A. Khan, P. Kyberd, D. Leslie, C. Munro, I.D. Reid,C. Siamitros, R. Taylor, L. Teodorescu, I. Yaselli

Boston University, Boston, USAT. Bose, M. Carleton, E. Hazen, A.H. Heering, A. Heister, J. St. John, P. Lawson, D. Lazic,D. Osborne, J. Rohlf, L. Sulak, S. Wu

Brown University, Providence, USAJ. Andrea, A. Avetisyan, S. Bhattacharya, J.P. Chou, D. Cutts, S. Esen, G. Kukartsev, G. Lands-berg, M. Narain, D. Nguyen, T. Speer, K.V. Tsang

University of California, Davis, Davis, USAR. Breedon, M. Calderon De La Barca Sanchez, M. Case, D. Cebra, M. Chertok, J. Conway,P.T. Cox, J. Dolen, R. Erbacher, E. Friis, W. Ko, A. Kopecky, R. Lander, A. Lister, H. Liu,S. Maruyama, T. Miceli, M. Nikolic, D. Pellett, J. Robles, M. Searle, J. Smith, M. Squires, J. Stilley,M. Tripathi, R. Vasquez Sierra, C. Veelken

University of California, Los Angeles, Los Angeles, USAV. Andreev, K. Arisaka, D. Cline, R. Cousins, S. Erhan1, J. Hauser, M. Ignatenko, C. Jarvis,J. Mumford, C. Plager, G. Rakness, P. Schlein†, J. Tucker, V. Valuev, R. Wallny, X. Yang

University of California, Riverside, Riverside, USAJ. Babb, M. Bose, A. Chandra, R. Clare, J.A. Ellison, J.W. Gary, G. Hanson, G.Y. Jeng, S.C. Kao,F. Liu, H. Liu, A. Luthra, H. Nguyen, G. Pasztor35, A. Satpathy, B.C. Shen†, R. Stringer, J. Sturdy,V. Sytnik, R. Wilken, S. Wimpenny

University of California, San Diego, La Jolla, USAJ.G. Branson, E. Dusinberre, D. Evans, F. Golf, R. Kelley, M. Lebourgeois, J. Letts, E. Lipeles,B. Mangano, J. Muelmenstaedt, M. Norman, S. Padhi, A. Petrucci, H. Pi, M. Pieri, R. Ranieri,M. Sani, V. Sharma, S. Simon, F. Würthwein, A. Yagil

University of California, Santa Barbara, Santa Barbara, USAC. Campagnari, M. D’Alfonso, T. Danielson, J. Garberson, J. Incandela, C. Justus, P. Kalavase,S.A. Koay, D. Kovalskyi, V. Krutelyov, J. Lamb, S. Lowette, V. Pavlunin, F. Rebassoo, J. Ribnik,J. Richman, R. Rossin, D. Stuart, W. To, J.R. Vlimant, M. Witherell

California Institute of Technology, Pasadena, USAA. Apresyan, A. Bornheim, J. Bunn, M. Chiorboli, M. Gataullin, D. Kcira, V. Litvine, Y. Ma,H.B. Newman, C. Rogan, V. Timciuc, J. Veverka, R. Wilkinson, Y. Yang, L. Zhang, K. Zhu,R.Y. Zhu

Carnegie Mellon University, Pittsburgh, USAB. Akgun, R. Carroll, T. Ferguson, D.W. Jang, S.Y. Jun, M. Paulini, J. Russ, N. Terentyev,H. Vogel, I. Vorobiev

29

University of Colorado at Boulder, Boulder, USAJ.P. Cumalat, M.E. Dinardo, B.R. Drell, W.T. Ford, B. Heyburn, E. Luiggi Lopez, U. Nauenberg,K. Stenson, K. Ulmer, S.R. Wagner, S.L. Zang

Cornell University, Ithaca, USAL. Agostino, J. Alexander, F. Blekman, D. Cassel, A. Chatterjee, S. Das, L.K. Gibbons, B. Heltsley,W. Hopkins, A. Khukhunaishvili, B. Kreis, V. Kuznetsov, J.R. Patterson, D. Puigh, A. Ryd, X. Shi,S. Stroiney, W. Sun, W.D. Teo, J. Thom, J. Vaughan, Y. Weng, P. Wittich

Fairfield University, Fairfield, USAC.P. Beetz, G. Cirino, C. Sanzeni, D. Winn

Fermi National Accelerator Laboratory, Batavia, USAS. Abdullin, M.A. Afaq1, M. Albrow, B. Ananthan, G. Apollinari, M. Atac, W. Badgett, L. Bagby,J.A. Bakken, B. Baldin, S. Banerjee, K. Banicz, L.A.T. Bauerdick, A. Beretvas, J. Berryhill,P.C. Bhat, K. Biery, M. Binkley, I. Bloch, F. Borcherding, A.M. Brett, K. Burkett, J.N. Butler,V. Chetluru, H.W.K. Cheung, F. Chlebana, I. Churin, S. Cihangir, M. Crawford, W. Dagenhart,M. Demarteau, G. Derylo, D. Dykstra, D.P. Eartly, J.E. Elias, V.D. Elvira, D. Evans, L. Feng,M. Fischler, I. Fisk, S. Foulkes, J. Freeman, P. Gartung, E. Gottschalk, T. Grassi, D. Green,Y. Guo, O. Gutsche, A. Hahn, J. Hanlon, R.M. Harris, B. Holzman, J. Howell, D. Hufnagel,E. James, H. Jensen, M. Johnson, C.D. Jones, U. Joshi, E. Juska, J. Kaiser, B. Klima, S. Kossiakov,K. Kousouris, S. Kwan, C.M. Lei, P. Limon, J.A. Lopez Perez, S. Los, L. Lueking, G. Lukhanin,S. Lusin1, J. Lykken, K. Maeshima, J.M. Marraffino, D. Mason, P. McBride, T. Miao, K. Mishra,S. Moccia, R. Mommsen, S. Mrenna, A.S. Muhammad, C. Newman-Holmes, C. Noeding,V. O’Dell, O. Prokofyev, R. Rivera, C.H. Rivetta, A. Ronzhin, P. Rossman, S. Ryu, V. Sekhri,E. Sexton-Kennedy, I. Sfiligoi, S. Sharma, T.M. Shaw, D. Shpakov, E. Skup, R.P. Smith†, A. Soha,W.J. Spalding, L. Spiegel, I. Suzuki, P. Tan, W. Tanenbaum, S. Tkaczyk1, R. Trentadue1, L. Up-legger, E.W. Vaandering, R. Vidal, J. Whitmore, E. Wicklund, W. Wu, J. Yarba, F. Yumiceva,J.C. Yun

University of Florida, Gainesville, USAD. Acosta, P. Avery, V. Barashko, D. Bourilkov, M. Chen, G.P. Di Giovanni, D. Dobur,A. Drozdetskiy, R.D. Field, Y. Fu, I.K. Furic, J. Gartner, D. Holmes, B. Kim, S. Klimenko,J. Konigsberg, A. Korytov, K. Kotov, A. Kropivnitskaya, T. Kypreos, A. Madorsky, K. Matchev,G. Mitselmakher, Y. Pakhotin, J. Piedra Gomez, C. Prescott, V. Rapsevicius, R. Remington,M. Schmitt, B. Scurlock, D. Wang, J. Yelton

Florida International University, Miami, USAC. Ceron, V. Gaultney, L. Kramer, L.M. Lebolo, S. Linn, P. Markowitz, G. Martinez, J.L. Ro-driguez

Florida State University, Tallahassee, USAT. Adams, A. Askew, H. Baer, M. Bertoldi, J. Chen, W.G.D. Dharmaratna, S.V. Gleyzer, J. Haas,S. Hagopian, V. Hagopian, M. Jenkins, K.F. Johnson, E. Prettner, H. Prosper, S. Sekmen

Florida Institute of Technology, Melbourne, USAM.M. Baarmand, S. Guragain, M. Hohlmann, H. Kalakhety, H. Mermerkaya, R. Ralich, I. Vo-dopiyanov

University of Illinois at Chicago (UIC), Chicago, USAB. Abelev, M.R. Adams, I.M. Anghel, L. Apanasevich, V.E. Bazterra, R.R. Betts, J. Callner,M.A. Castro, R. Cavanaugh, C. Dragoiu, E.J. Garcia-Solis, C.E. Gerber, D.J. Hofman, S. Kha-latian, C. Mironov, E. Shabalina, A. Smoron, N. Varelas


The University of Iowa, Iowa City, USAU. Akgun, E.A. Albayrak, A.S. Ayan, B. Bilki, R. Briggs, K. Cankocak36, K. Chung, W. Clarida,P. Debbins, F. Duru, F.D. Ingram, C.K. Lae, E. McCliment, J.-P. Merlo, A. Mestvirishvili,M.J. Miller, A. Moeller, J. Nachtman, C.R. Newsom, E. Norbeck, J. Olson, Y. Onel, F. Ozok,J. Parsons, I. Schmidt, S. Sen, J. Wetzel, T. Yetkin, K. Yi

Johns Hopkins University, Baltimore, USAB.A. Barnett, B. Blumenfeld, A. Bonato, C.Y. Chien, D. Fehling, G. Giurgiu, A.V. Gritsan,Z.J. Guo, P. Maksimovic, S. Rappoccio, M. Swartz, N.V. Tran, Y. Zhang

The University of Kansas, Lawrence, USAP. Baringer, A. Bean, O. Grachov, M. Murray, V. Radicci, S. Sanders, J.S. Wood, V. Zhukova

Kansas State University, Manhattan, USAD. Bandurin, T. Bolton, K. Kaadze, A. Liu, Y. Maravin, D. Onoprienko, I. Svintradze, Z. Wan

Lawrence Livermore National Laboratory, Livermore, USAJ. Gronberg, J. Hollar, D. Lange, D. Wright

University of Maryland, College Park, USAD. Baden, R. Bard, M. Boutemeur, S.C. Eno, D. Ferencek, N.J. Hadley, R.G. Kellogg, M. Kirn,S. Kunori, K. Rossato, P. Rumerio, F. Santanastasio, A. Skuja, J. Temple, M.B. Tonjes, S.C. Ton-war, T. Toole, E. Twedt

Massachusetts Institute of Technology, Cambridge, USAB. Alver, G. Bauer, J. Bendavid, W. Busza, E. Butz, I.A. Cali, M. Chan, D. D’Enterria, P. Everaerts,G. Gomez Ceballos, K.A. Hahn, P. Harris, S. Jaditz, Y. Kim, M. Klute, Y.-J. Lee, W. Li, C. Loizides,T. Ma, M. Miller, S. Nahn, C. Paus, C. Roland, G. Roland, M. Rudolph, G. Stephans, K. Sumorok,K. Sung, S. Vaurynovich, E.A. Wenger, B. Wyslouch, S. Xie, Y. Yilmaz, A.S. Yoon

University of Minnesota, Minneapolis, USAD. Bailleux, S.I. Cooper, P. Cushman, B. Dahmes, A. De Benedetti, A. Dolgopolov, P.R. Dudero,R. Egeland, G. Franzoni, J. Haupt, A. Inyakin37, K. Klapoetke, Y. Kubota, J. Mans, N. Mirman,D. Petyt, V. Rekovic, R. Rusack, M. Schroeder, A. Singovsky, J. Zhang

University of Mississippi, University, USAL.M. Cremaldi, R. Godang, R. Kroeger, L. Perera, R. Rahmat, D.A. Sanders, P. Sonnek, D. Sum-mers

University of Nebraska-Lincoln, Lincoln, USAK. Bloom, B. Bockelman, S. Bose, J. Butt, D.R. Claes, A. Dominguez, M. Eads, J. Keller, T. Kelly,I. Kravchenko, J. Lazo-Flores, C. Lundstedt, H. Malbouisson, S. Malik, G.R. Snow

State University of New York at Buffalo, Buffalo, USAU. Baur, I. Iashvili, A. Kharchilava, A. Kumar, K. Smit

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Performance of the CMS Hadron Calorimeter with Cosmic Ray ... · CMS PAPER CFT-09-009 CMS Paper 2010/01/01 Performance of the CMS Hadron Calorimeter with Cosmic Ray Muons and LHC