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Digital Hadron Calorimeter (DHCAL) José Repond Argonne National Laboratory CLIC Workshop 2013 January 28 – February 1, 2013 CERN, Geneva, Switzerland

Digital Hadron Calorimeter (DHCAL)

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Digital Hadron Calorimeter (DHCAL). José Repond Argonne National Laboratory. CLIC Workshop 2013 January 28 – February 1, 2013 CERN, Geneva, Switzerland. The Digital Hadron Calorimeter (DHCAL) I. Active element Thin Resistive Plate Chambers (RPCs) Glass as resistive plates - PowerPoint PPT Presentation

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Page 1: Digital Hadron  Calorimeter  (DHCAL)

Digital Hadron Calorimeter (DHCAL)

José RepondArgonne National Laboratory

CLIC Workshop 2013 January 28 – February 1, 2013

CERN, Geneva, Switzerland

Page 2: Digital Hadron  Calorimeter  (DHCAL)

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The Digital Hadron Calorimeter (DHCAL) IActive element

Thin Resistive Plate Chambers (RPCs)

Glass as resistive plates Single 1.15 mm thick gas gap

Readout

1 x 1 cm2 pads 1-bit per pad/channel → digital readout 100-ns level time-stamping Virtually dead-time free

Calorimeter

54 active layers

1 x 1 m2 planes with each 9,216 readout channels 3 RPCs (32 x 96 cm2) per plane

Absorber

Either Steel or Tungsten

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The Digital Hadron Calorimeter (DHCAL) II

DHCAL = First large scale calorimeter prototype with

Embedded front-end electronics Digital (= 1 – bit) readout Pad readout of RPCs (RPCs usually read out with strips) Extremely fine segmentation with 1 x 1 cm2 pads

DHCAL = World record channel count for calorimetry World record channel count for RPC-based systems

497,664 readout channels

DHCAL construction

Started in Fall 2008 Completed in January 2011

Test beam activities

~ 5 months in the Fermilab testbeam (Steel absorber) ~ 6 weeks in the CERN testbeams (Tungsten absorber)

This is only a prototypeFor a colliding beam detector multiply by ×50

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DHCAL Construction Fall 2008 – Spring 2011

Resistive Plate Chamber

Sprayed 700 glass sheets Over 200 RPCs assembled → Implemented gas and HV connections

Electronic Readout System

10,000 ASICs produced (FNAL) 350 Front-end boards produced

→ glued to pad-boards 35 Data Collectors built

6 Timing and Trigger Modules built

Assembly of Cassettes

54 cassettes assembledEach with 3 RPCs

and 9,216 readout channels

350,208 channel system in first test beam Event displays 10 minutes after closing enclosure

Extensive testing at every step

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Testing in BeamsFermilab MT6

October 2010 – November 2011 1 – 120 GeV Steel absorber (CALICE structure)

CERN PS

May 2012 1 – 10 GeV/c Tungsten absorber (structure provided by CERN)

CERN SPS

June – November 2012 10 – 300 GeV/c Tungsten absorber

Test Beam Muon events Secondary beam

Fermilab 9.4 M 14.3 M

CERN 5.6 M 23.4 M

TOTAL 15.0 M 37.8 M

A unique data sample

RPCs flown to GenevaAll survived transportation

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First R&W Digital Photos of Hadronic Showers

Configuration with minimal

absorber

μ

μ 120 GeV p

8 GeV e+ 16 GeV π+

Note: absence of isolated noise hits

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Noise studiesSeveral data sets

Random trigger runs Trigger-less runs (all hits recorded) Triggered data (first 2/7 time bins)

Average noise rate

Depends on temperature and ambient pressure

Impact on analyses/measurements

Noise rate negligible for linearity/resolution Possible effect on shower shape measurements

→ Requires detailed studies

Time distribution of hits far from shower axis

Time →

Nnoise = 0.01 ÷ 0.1 hits/event in the entire DHCAL~15 hits correspond to 1 GeV

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Measurements with Muons

Performance of the chambers

Established through measurement of response to muons

Simulation

RPC response tuned to reproduce signal from muons

DHCAL

TCMT

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Scan across a single 1× 1 cm2 pad x = Mod(xtrack,1.0) for 0.25 < y < 0.75y = Mod(ytrack,1.0) for 0.25 < x < 0.75

Note: these features not explicitly implemented into simulation. Result of properly distributing charge over surface of readout pads

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Results - October 2010 Data

Gaussian fits over the full response curve

Unidentified μ's, punch through

CALICE Preliminary

Fe absorber

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Pion Selection

Standard pion selection+ No hits in last two layers (longitudinal containment

16 (off), 32 GeV/c (effects of saturation expected) data points are not included in the fit.

N=aE

CALICE Preliminary(response not calibrated)

Fe absorber

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Standard pion selection+ No hits in last two layers (longitudinal containment)

32 GeV data point is not included in the fit.

CALICE Preliminary(response not yet calibrated)

C E

α=Eσ ⊕

B. Bilki et.al. JINST4 P10008, 2009.

MC predictions for a large-size DHCAL based on the Vertical Slice Test.

α= 58%

Pion Selection

Fe absorber

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CALICE Preliminary(response not yet calibrated)

Correction for non-linearity Needed to establish resolution Correction on an event-by-event basis

N=a+bEm

B. Bilki et.al. JINST4 P04006, 2009.

Data (points) and MC (red line) for the Vertical Slice Test and the MC predictions for a large-size DHCAL (green, dashed line).

Positron SelectionFe absorber

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Positron Selection

Correction for Non-Linearity

Fe absorber

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Uncorrected for non-linearityCorrected for non-linearity

CALICE Preliminary(response not calibrated)

C E

α=Eσ ⊕

Positron SelectionFe absorber

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Transportation to CERN

Transport fixture

Specially built for transportation to CERN Shocks dampened with help of 9 springs

Flown to CERN

DHCAL cassettes Readout system Gas mixing rack Gas distribution rack Low voltage power supplies High voltage system

RPCs

Survived transportation to CERN Now back at Argonne (not tested yet)

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Response at the PS (1 – 10 GeV)

Fluctuations in muon peak

Data not yet calibrated

Response non-linear

Data fit empirically with αEβ

β= 0.90 (hadrons), 0.78 (electrons)

W-DHCAL with 1 x 1 cm2

Highly over-compensating (smaller pads would increase the electron response more than the hadron response)

Remember: W-AHCAL is compensating!

W absorber

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Resolution at the PS (1 – 10 GeV)

Resolutions corrected for non-linear response

Data fit with quadratic sum of constant and stochastic term

Ec

E

Particle α c

Pions (68.0±0.4)% (5.4±0.7)%Electrons (29.4±0.3)% 16.6±0.3)%

(No systematics yet)

W absorber

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Comparison with Simulation – SPS energies

Data

Uncalibrated Tails toward lower Nhit

Simulation

Tuned to Fe-DHCAL data (different operating condition) Rescaled to match peaks Shape surprisingly well reproduced

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Response at the SPS (12 – 300 GeV)

Fluctuations in muon peak

Data not yet calibrated

Response non-linear

Data fit empirically with αEβ

β= 0.85 (hadrons), 0.70 (electrons)

W-DHCAL with 1 x 1 cm2

Highly over-compensating (smaller pads would increase the electron response more than the hadron response)

W absorber

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Institute

Argonne National Laboratory

IHEP Beijing

Boston University

CERN

COE college

Fermilab

Illinois Institute of Technology

University of Iowa

McGill University

Northwestern

University of Oregon

University of Texas at Arlington

Contributors to the DHCAL Project

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Final RemarksDHCAL performed as expected and validates technical approach DHCAL is a novel detector

Many studies ongoing on

Calibration (response) Calibration (optimized for resolution) Noise Software compensation…

Further R&D needed to design a ‘module 0’

LV/HV distribution Gas distribution and recycling 1-glass RPC design Development of semi-conductive glass (for high rate operation) RPC assembly techniques…