Post on 23-Mar-2016
description
Digital Hadron Calorimeter (DHCAL)
José RepondArgonne National Laboratory
CLIC Workshop 2013 January 28 – February 1, 2013
CERN, Geneva, Switzerland
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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…