LHCF S
TATU
S AND
RESULTS
OS C A R
A DR
I AN
I ON
B E HA L F O
F T HE L H
C F C OL L A B O
R A T I ON
CERN, 23 MARCH 2011
O SC A R A D R I AN I L H C C M E E T I N G , C E R N 2 3 M A RC H 2 0 1 1
HECR OPEN ISSUES
Difference in the energy scale between different experiments???
The depth of the maximum of the shower Xmax depends on energy and type of the primary particle
AGASA x 0.9AUGER x 1.3
Different hadronic interaction models give different answers about the composition of HECR
M NaganoNew Journal of Physics 11 (2009) 065012
O SC A R A D R I AN I L H C C M E E T I N G , C E R N 2 3 M A RC H 2 0 1 1
Detectors installed in the TAN region, 140 m away from ATLAS Interaction Point (IP1)
Charged particles
Neutral particles
Beam pipe
Protons
LHCF EXPERIMENTAL SET-UP
Here the beam pipe splits in 2 separate tubes. Charged particle are swept away by magnets We will cover |h|>8
Front Counters: thin scintillators with 8x8cm2 acceptance installed in front of each main detector
ARM1 & ARM2 DETECTORSARM1
2 towers 24 cm long
stacked vertically
with 5 mm gap
Lower: 2 cm x 2 cm
areaUpper: 4 cm x 4 cm
area
Arm#190mm
290mm
Arm#2
O S C A R AD R I AN I L H C C M E E T I N G , C E R N 2 3 M ARC H 2 0 1 1
ARM22 towers 24 cm long stacked on their edges and offset from one anotherLower: 2.5 cm x 2.5 cmUpper: 3.2 cm x 3.2 cm
16 scintillator layers (3 mm thick)Trigger and energy profile measurements
Energy
Impact point (h)
4 pairs of scintillating fiber layers for tracking purpose (6, 10, 32, 38 r.l.)
4 pairs of silicon microstrip layers (6, 12, 30, 42 r.l.) for tracking purpose (X and Y directions) Absorber
22 tungsten layers 7– 14 mm thick (2-4 r.l.) (W: X0 = 3.5mm, RM = 9mm)
O S C AR A D R I A N I L H C C M E E T I N G , C E RN 2 3 M A RC H 2 0 1 1
INCLUSIVE P
HOTON
SPECTR
UM ANALYSIS
L H C F DA T A T
A K I NG
O SC A R A D R I AN I L H C C M E E T I N G , C E R N 2 3 M A RC H 2 0 1 1
LHCF OPERATIONS @900 GEV & 7 TEV
With Stable Beam at 900 GeV Dec 6th – Dec 15th 2009With Stable Beam at 900 GeV May 2nd – May 27th 2010
With Stable Beam at 7 TeV March 30th - July 19th
We took data with and without 100 μrad crossing angle for different vertical detector positions
Shower Gamma Hadron π0
Arm1 172,263,255 56,846,874 111,971,115 344,526
Arm2 160,587,306 52,993,810 104,381,748 676,157
Shower Gamma Hadron
Arm1 46,800 4,100 11,527
Arm2 66,700 6,158 26,094
LHCf Status Report
O SC A R A D R I AN I L H C C M E E T I N G , C E R N 2 3 M A RC H 2 0 1 1
DATA SET FOR INCLUSIVE PHOTON SPECTRUM ANALYSIS• Data–Date : 15 May 2010 17:45-21:23 (Fill Number : 1104) except runs during the luminosity scan. –Luminosity : (6.5-6.3)x1028cm-2s-1,–DAQ Live Time : 85.7% for Arm1, 67.0% for Arm2–Integrated Luminosity : 0.68 nb-1 for Arm1, 0.53nb-1 for Arm2 –Number of triggers : 2,916,496 events for Arm1
3,072,691 events for Arm2 –Detectors in nominal positions and Normal Gain• Monte Carlo–QGSJET II-03, DPMJET 3.04, SYBILL 2.1, EPOS 1.99 and PYTHIA8.145: about 107 pp inelastic collisions each LHCf Status Report
O SC A R A D R I AN I L H C C M E E T I N G , C E R N 2 3 M A RC H 2 0 1 1
1 TEV p0 CANDIDATE EVENT
A p0 candidate event599GeV gamma-ray and 419GeV gamma-ray in 25mm and 32mm tower respectively.
LHCf Status Report
Longitudinal profile
Transverse profile
O SC A R A D R I AN I L H C C M E E T I N G , C E R N 2 3 M A RC H 2 0 1 1
LUMINOSITY ESTIMATIONLuminosity for the analysis is calculated from Front
Counter rates:
The conversion factor CF is estimated from luminosity measured during Van der Meer scan
VDM scan
BCNWG paperhttps://lpc-afs.web.cern.ch/lpc-afs/tmp/note1_v4_lines.pdf
Beam sizes sx and sy measured directly by LHCf
LHCf Status Report
O S C AR A D R I A N I L H C C M E E T I N G , C E RN 2 3 M A RC H 2 0 1 1
PARTIC
LE
IDENTIF
ICATION
O SC A R A D R I AN I L H C C M E E T I N G , C E R N 2 3 M A RC H 2 0 1 1
•QGSJET2-gamma and -hadron are normalized to data(/collision) independently• LPM effects are switched on
Particle IdentificationPID criteria based on transition curve
500 GeV <EREC<1 TeV
MC/Data comparison done in many energy bins
LHCf Status Report
O SC A R A D R I AN I L H C C M E E T I N G , C E R N 2 3 M A RC H 2 0 1 1
PID CORRECTIONEfficiency and purity for gamma-ray estimated from L90% fitting with MC template (QGSJET2).
Hatched : data Red : true-gamma Blue : true-hadron Green : Red+BlueBin by bin (energy) correction applied to take into account shape disagreement between Data/MC (see systematic error section)
LHCf Status Report
O S C AR A D R I A N I L H C C M E E T I N G , C E RN 2 3 M A RC H 2 0 1 1
ENER
GY SCALE IS
SUE
O SC A R A D R I AN I L H C C M E E T I N G , C E R N 2 3 M A RC H 2 0 1 1
p0 MASS Arm1 Data
Peak at 145.8 ± 0.1 MeV
• Disagreement in the peak position• No ‘hand made correction’ is applied for safety• Main source of systematic error see later
Arm2 Data
Arm2 MC(QGSJET2)
Peak at 140.0 ± 0.1 MeV
Peak at 135.0 ± 0.2 MeV3.8 % shift
Many systematic checks have been done to understand the energy scale difference
LHCf Status Report
7.8 % shift
O SC A R A D R I AN I L H C C M E E T I N G , C E R N 2 3 M A RC H 2 0 1 1
p0 MASS VS p0 ENERGY
Arm2 DataNo strong energy dependence of reconstructed mass
LHCf Status Report
O SC A R A D R I AN I L H C C M E E T I N G , C E R N 2 3 M A RC H 2 0 1 1
h MASS Arm2 detector, all runs with zero crossing angleTrue h Mass: 547.9 MeVMC Reconstructed h Mass peak: 548.5 ± 1.0 MeVData Reconstructed h Mass peak: 562.2 ± 1.8 MeV (2.6% shift)
LHCf Status Report
O S C AR A D R I A N I L H C C M E E T I N G , C E RN 2 3 M A RC H 2 0 1 1
MULTI HIT
REJECTIO
N
O SC A R A D R I AN I L H C C M E E T I N G , C E R N 2 3 M A RC H 2 0 1 1
MULTI-HIT REJECTIONIn order to extract inclusive single gamma spectra, rejection of multi-hit events is mandatory especially at high energy (> 2.5 TeV)
LHCf Status Report
O SC A R A D R I AN I L H C C M E E T I N G , C E R N 2 3 M A RC H 2 0 1 1
MULTI-HIT REJECTIONMulti-hit events are identified thanks to position sensitive layers in ARM1 (SciFi) and Arm2 (Si-mstrip)
LHCf Status Report
O SC A R A D R I AN I L H C C M E E T I N G , C E R N 2 3 M A RC H 2 0 1 1
MULTI-HIT REJECTION
LHCf Status Report
Single gamma detection efficiency for various MC models
Multi gamma detection efficiency for various MC models
Please have a look to systematic error section!
O S C AR A D R I A N I L H C C M E E T I N G , C E RN 2 3 M A RC H 2 0 1 1
RESULTS
O SC A R A D R I AN I L H C C M E E T I N G , C E R N 2 3 M A RC H 2 0 1 1
ACCEPTANCE CUT
R1 = 5mmR2-1 = 35mmR2-2 = 42mmq = 20o
For Small Tower h > 10.94 For Large Tower8.81 < h < 8.99
We define in each tower a region common both to Arm1 and Arm2, to compare the Arm1 and Arm2 reconstructed spectra.
Our final results will be two spectra, one for each acceptance region, obtained by properly weighting the Arm1 and Arm2 spectra
LHCf Status Report
O SC A R A D R I AN I L H C C M E E T I N G , C E R N 2 3 M A RC H 2 0 1 1
ARM1 AND ARM2 COMPARISON
- Multi-hit rejection and PID correction applied- Energy scale systematic not considered due to strong correlation between Arm1 and Arm2
Deviation in small tower: still unclear, but within systematic errors
LHCf Status Report
O SC A R A D R I AN I L H C C M E E T I N G , C E R N 2 3 M A RC H 2 0 1 1
COMBINED SPECTRA AND COMPARISON WITH MODELS
Arm1 and Arm2 combined spectra including syst. errors
Gray hatched:stat.+syst. errorBlue hatched:QGSJET2 stat. error
LHCf Status Report
O S C AR A D R I A N I L H C C M E E T I N G , C E RN 2 3 M A RC H 2 0 1 1
SYSTEMATIC
UNCERTA
INTIES
E N E R G Y S C A L E , M U L T I - H I T , B E A M C E N T E R , P I D , L U M I N O S I T Y
O SC A R A D R I AN I L H C C M E E T I N G , C E R N 2 3 M A RC H 2 0 1 1
SYSTEMATIC UNCERTAINTIES
Uncorrelated uncertainties between ARM1 and ARM2- Energy scale (except p0 error)- Beam center position- PID- Multi-hit selection
Correlated uncertainty- Energy scale (p0 error)- Luminosity error
Estimated for Arm1 and Arm2 by same methods but independently
Estimated by Arm2, and apply it to the both Arm
LHCf Status Report
O SC A R A D R I AN I L H C C M E E T I N G , C E R N 2 3 M A RC H 2 0 1 1
SYSTEMATIC ERROR FROM ENERGY SCALE
Two components:- Relatively well known: Detector response, SPS => 3.5%- Unknown: p0 mass => 7.8%, 3.8% for Arm1 and Arm2.
Please note: - 3.5% is symmetric around measured energy
- 7.8% (3.8%) are asymmetric, because of the p0
mass shift- No ‘hand made’ correction is applied up to now for safety
Total uncertainty is -9.8% / +1.8% for Arm1 -6.6% / +2.2% for Arm2
Systematic Uncertainty on Spectra is estimated from difference between normal spectra and energy shifted spectra.
LHCf Status Report
O SC A R A D R I AN I L H C C M E E T I N G , C E R N 2 3 M A RC H 2 0 1 1
BEAM CENTER POSITIONError of beam center position is estimated to be 1 mm from comparison between our results and the BPM results The systematic errors on spectra were estimated from the difference between spectra with 1 mm shift of acceptance cut area. (Small tower, true single-gamma) (Large tower, true single-gamma)
Fluctuation in HE is probably statistical
100 GeV<E<3.5 TeV : 5%
100 GeV<E<2.5 TeV : 10%E>2.5 TeV : 20%
Arm1 Results
LHCf Status Report
O SC A R A D R I AN I L H C C M E E T I N G , C E R N 2 3 M A RC H 2 0 1 1
SYSTEMATIC ERROR FROM PID
Template fitting A: 1 degree of freedom: - Absolute normalization
Template fitting B: 3 degrees of freedom: - Absolute normalization - Shift of L90% distribution - Width of L90% distribution
Efficiency and purity are estimated with two different approaches
Hatched : dataRed : true-gammaBlue : true-hadronGreen : Red+Blue
Systematic error from PID:100GeV<E<1.7TeV : 5%1.7TeV<E : 20%Both on small and large tower
Arm1
LHCf Status Report
O SC A R A D R I AN I L H C C M E E T I N G , C E R N 2 3 M A RC H 2 0 1 1
SYSTEMATIC ERROR FROM MHSystematic error is estimated from the deformation factor of original MC spectrum wrt reconstructed MC spectrum for various models
LHCf Status Report
True
/Rec
onst
ruct
ed
True
/Rec
onst
ruct
ed
O SC A R A D R I AN I L H C C M E E T I N G , C E R N 2 3 M A RC H 2 0 1 1
CONCLUSIONS• LHCf Inclusive photon analysis has been completed
• Many detailed systematic checks were necessary!• ‘Very safe’ estimation of systematics• First comparison of variuos hadronic interaction models with
experimental data in the most challenging phase space region (8.81 < h < 8.99, h > 10.94)
• Other analysis are in progress (hadrons, PT distributions, different h coverage etc.)
• We are upgrading the detectors to improve their radiation hardness (GSO scintillators)
• Discussion are under way to come back in the TAN for the possible p-Pb run in 2013 (LHCC, Alice, LHC, Atlas etc.)
• We will anyway come back for the 14 TeV run with upgraded detector!!!!
LHCf Status Report
O S C A R AD R I AN I L H C C M E E T I N G , C E R N 2 3 M ARC H 2 0 1 1
A SPECIAL THOUGHT FOR JAPAN
O S C AR A D R I A N I L H C C M E E T I N G , C E RN 2 3 M A RC H 2 0 1 1
BACK-UP SLID
ES
O SC A R A D R I AN I L H C C M E E T I N G , C E R N 2 3 M A RC H 2 0 1 1
⇔ΔXmax (DPMJETⅢ-QGSJETⅡ) = 36g/cm2
Transition curve for 1017eV proton
π0 reconstructed spectrum
Xmax = 696.6g/cm2 ± 2.3 +15.9, -7.8 g/cm2
statisticalsystematic
IMPACT OF LHCF ON CR PHYSICS
O SC A R A D R I AN I L H C C M E E T I N G , C E R N 2 3 M A RC H 2 0 1 1
LUMINOSITY DURING THE VDM SCANS
Fill 1059 (26th April)
Fill 1089 (09th May)
beam1 8.98±0.34 N(1)10.20±0.38 N(17851)
18.99±0.54 N(1)19.08±0.54 N(17851)
beam2 10.35±0.37 N(1)10.35±0.37 N(8911)
22.18±0.61 N(1)21.21±0.59 N(8911)
beam1*2 92.94 N(1) 421.20 N(1)
Luminosity (/cm2s)
FC1 2.01E+28FC2 2.00E+28FC1&2
2.09E+28
26th April 2010 9th May 2010Luminosity (/cm2s)
FC1 5.90E+27FC2 6.04E+27FC1&2
5.99E+27Intensity information
LHCf Status Report
O S C A R AD R I AN I L H C C M E E T I N G , C E R N 2 3 M ARC H 2 0 1 1
LUMINOSITY ERRORS
contents errorIntensity2 5.0%Difference between April scan & May scan 2.1%Difference between arm1&2 2.7%Total 6.1%
Total systematic uncertainty due to luminosity was estimated to be 6.1%
LHCf Status Report
O S C A R AD R I AN I L H C C M E E T I N G , C E R N 2 3 M ARC H 2 0 1 1
ESTIMATION OF PILE UPWhen the circulated bunch is 1x1, the probability of N collisions per Xing is
The ratio of the pile up event is
The maximum luminosity per bunch during runs used for the analysis is 2.3x1028cm-2s-1
So the probability of pile up is estimated to be 7.2% with σ of 71.5mbTaking into account the calorimeter acceptance (~0.03) only 0.2% of events have multi-hit due to pile-up. It does not affect our results
LHCf Status Report
O SC A R A D R I AN I L H C C M E E T I N G , C E R N 2 3 M A RC H 2 0 1 1
ENERGY RECONSTRUCTION AT SPSDifference of energy reconstruction at SPS between data and MC is < 1%.Systematic error for gain calibration factor layer by layer is 2%
LHCf Status Report
O SC A R A D R I AN I L H C C M E E T I N G , C E R N 2 3 M A RC H 2 0 1 1
COMPARISON OF EJ260 AND GSO-PULSE SHAPE-• Response for the N2 (Nitrogen) LASER• pulse width is ~300ps ( fast enough)• EJ260 : ~12ns decay time• GSO : 30~40ns decay time• Roughly similar decay time
EJ260
GSO
LHCf Status Report
O SC A R A D R I AN I L H C C M E E T I N G , C E R N 2 3 M A RC H 2 0 1 1
COMPARISON OF EJ260 AND GSO-RADIATION HARDNESS-
• EJ260 (HIMAC* Carbon beam)10% decrease of light yield after exposure of 100Gy
• GSO (HIMAC Carbon beam)No decrease of light yield even after 7*10^5Gy exposure,BUT increase of light yield is confirmed
• The increase depend on irradiation rate (~2.5%/[100Gy/hour])*HIMAC : Heavy Ion Medical Accelerator in Chiba
LHCf Status Report
O SC A R A D R I AN I L H C C M E E T I N G , C E R N 2 3 M A RC H 2 0 1 1
LINEARITY OF PMT R7400• PMTs R7400 are used in current LHCf system• The test was held in HIMAC using Xe beam• PMT R7400 showed good linearity within 1% up to
signal level corresponding to 6TeV showerMAX in LHCf.
LHCf Status Report