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CMS combined ECAL and HCAL testbeam 2006
Nuclear Physics B (Proc. Suppl.) 172 (2007) 126–128 www.elsevierphysics.com
CMS combined ECAL and HCAL testbeam 2006 Lisa Berntzon
a∗
.
a
Department of Physics, Texas Tech University, Box 41051, Lubbock, Texas 79409-1051, USA The response of the CMS combined electromagnetic and hadronic calorimeters has been measured at the CERN H2 test beam in the summer of 2006 using pions, (anti-)protons, electrons, and muons in momentum range from 1 to 350 GeV/c. Preliminary results from the these studies will be discussed. Subdetector modules consisting of two HCAL Barrel (HB) wedges (2 × 20◦ ), three HCAL Outer (HO) rings (40◦ ), one HCAL Endcap (HE) wedge (20◦ ) and one ECAL Barrel (EB) supermodule (20◦ ) were mounted on a movable table which enabled us to mimic the directions of particles originating from the LHC interaction point. These tests are essential for correctly reconstructing the calorimetry response, especially of jets.
1. Introduction The Compact Muon Solenoid (CMS) [1] detector is a general purpose detector to be installed in the 14 TeV Large Hadron Collider (LHC), under construction at CERN. The physics program at CMS requires detailed measurements of quark and gluon jets as well as missing transverse energy. Thus, a high performing calorimeter system is needed. This talk gives a short overview of the beam test activities in 2006 of the combined CMS calorimeter system. For the first time, the response of the CMS combined electromagnetic and hadronic calorimeters has been measured in a beam test. The beam test was carried out at the CERN North Area H2 test beam with various particle types in a wide momentum range (1 ≤ p ≤ 350 GeV/c). The previous beam test of 2004 had used a mock-up of the CMS electromagnetic calorimeter consisting of only 7 × 7 PbWO4 crystals read out by photomultipliers, whereas this test used an actual CMS ECAL supermodule. 2. Experimental setup The CMS electromagnetic calorimeter (ECAL) [2], is a homogeneous calorimeter made of scintillating lead tungsten PbWO4 crystals [3]. ∗ for
the CMS Collaboration
0920-5632/$ – see front matter © 2007 Elsevier B.V. All rights reserved. doi:10.1016/j.nuclphysbps.2007.07.015
The central barrel part (EB) consists of 36 supermodules made by 61,200 crystals and is closed by the two endcaps containing 7,324 crystals. Each EB supermodule covers half the barrel length and 20◦ in azimuth. The CMS Hadron Calorimeter (HCAL) [4,5], is designed to measure hadron jets, single hadrons and single muons. In the CMS detector, the central Hadronic Barrel detector (HB) and the Hadronic Endcap detectors (HE) are sampling calorimeters, made of brass and plastic scintillators, and cover the pseudorapidity region of −3 ≤ η ≤ 3. The HB and HE detectors are located inside the 13 m long 4T solenoid magnet. Central shower containment is improved by the Hadronic Outer detector (HO) which is composed of 2 scintillator layers outside the magnet. Forward calorimeters that cover 3 ≤ η ≤ 5 are constructed using quartz fibers in steel absorber and were not part of the 2006 test beam work. In the beam test of 2006, two HB wedges (2 × 20◦ in azimuth), three HO rings (40◦ ), one HE wedge (20◦ ) and one ECAL Barrel supermodule (20◦ ) were mounted on a movable table which enabled us to mimic the directions of particles originating from the LHC interaction point. The H2 beamline was much improved as compared to the previous beam test of 2004, with better particle identification and ability to reject particles produced in beamline interactions.
L. Berntzon / Nuclear Physics B (Proc. Suppl.) 172 (2007) 126–128
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Figure 1. Layout of the H2 beamline in VLE mode. Two beamline configurations were used, for momenta above 10 GeV/c the high energy and for momenta below 10 GeV/c the Very Low Energy (VLE) mode. In order to generate beams with momenta less than 10 GeV/c, a tertiary target (T22) is inserted, and a beamstop was positioned into the high energy section, see Fig. 1. Additional beam focusing and bending elements are used along the VLE path in order to achieve a well defined beam momentum in the range of 1 to 9 GeV/c. Scintillation counters provide trigger and some particle identification information. The trigger signal was created using three scintillation counters, S1(14 × 14 cm2 ) · S2 (4 × 4 cm2 ) · S4(14 × 14 cm2 ). Four large scintillation counters were placed directly after the trigger scintillators and used as beam halo veto. Further scintillation counters were installed between the HB and the HO detectors, as well as behind the HO to identify muons. The beamline was also equipped with Cherenkov counters, time-of-flight detectors and several wire chambers, as shown in Fig. 1. Through the use of Cherenkov threshold, timeof-flight detectors, and the scintillation counters we are able to identify (anti-)protons, kaons, pions, muons and electrons. This beam line is unique, and is particularly well-suited for calorimetry. 3. Preliminary Results The data sets collected include calibration data (for the HCAL using electrons, muons and radioactive source), intercalibration data for the
ECAL, energy scans at both high and low energy, eta and phi scans, crack studies and longitudinal shower profiles of the HB. The relative calibration of each HCAL scintillator was determined using a moving-wire radioactive source. In Fig. 2 the HCAL versus ECAL response to 5 GeV/c π + is shown without any particle identification criteria applied, and in Fig. 3 the remaining events are shown after all π + selection criteria have been applied. 4. Conclusion The features of the ECAL and HCAL response have been measured in detail with different particles and energies. The improved beamline provides various types of particles in the momentum range from 1 to 350 GeV/c. For the first time, we have a complete set of low energy data for electrons, pions, kaons and (anti-)protons for the combined CMS ECAL and HCAL calorimeters. These data are essential to correctly estimate the jet response of the CMS calorimeter system and the detailed analyses are underway. REFERENCES 1. CMS Collaboration, ’The Compact Muon Solenoid Technical Proposal’, CERN/LHCC 94-38, 1994 2. CMS Collaboration, ’The electromagnetic calorimeter project. Technical Design Report’, CERN/LHCC 1997-033, 1997. 3. A. A. Annenkov, P. Lecoq and M. V. Korzik,
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L. Berntzon / Nuclear Physics B (Proc. Suppl.) 172 (2007) 126–128
Figure 2. HCAL vs ECAL response to 5 GeV/c π + is shown before any beam cleaning criteria are applied.
’Lead Tungsten scintillation material’, Nucl. Instr. and Meth. A490 (2002) 30. 4. CMS Collaboration, ’The Hadron Calorimeter Technical Design Report’, CERN/LHCC 1997-032, CMS TDR 3, (1997). 5. S. Abdullin et al. CMS HCAL Collaboration, ’Design, Performance and Calibration of CMS Hadron-Barrel Calorimeter Wedges’, submitted to Nucl. Inst. Meth.
Figure 3. Same as Fig. 2 but all π + selection criteria are applied. Note, for example, the electron contamination is efficiently removed.
CMS combined ECAL and HCAL testbeam 2006 Lisa Berntzon
a∗
.
a
Department of Physics, Texas Tech University, Box 41051, Lubbock, Texas 79409-1051, USA The response of the CMS combined electromagnetic and hadronic calorimeters has been measured at the CERN H2 test beam in the summer of 2006 using pions, (anti-)protons, electrons, and muons in momentum range from 1 to 350 GeV/c. Preliminary results from the these studies will be discussed. Subdetector modules consisting of two HCAL Barrel (HB) wedges (2 × 20◦ ), three HCAL Outer (HO) rings (40◦ ), one HCAL Endcap (HE) wedge (20◦ ) and one ECAL Barrel (EB) supermodule (20◦ ) were mounted on a movable table which enabled us to mimic the directions of particles originating from the LHC interaction point. These tests are essential for correctly reconstructing the calorimetry response, especially of jets.
1. Introduction The Compact Muon Solenoid (CMS) [1] detector is a general purpose detector to be installed in the 14 TeV Large Hadron Collider (LHC), under construction at CERN. The physics program at CMS requires detailed measurements of quark and gluon jets as well as missing transverse energy. Thus, a high performing calorimeter system is needed. This talk gives a short overview of the beam test activities in 2006 of the combined CMS calorimeter system. For the first time, the response of the CMS combined electromagnetic and hadronic calorimeters has been measured in a beam test. The beam test was carried out at the CERN North Area H2 test beam with various particle types in a wide momentum range (1 ≤ p ≤ 350 GeV/c). The previous beam test of 2004 had used a mock-up of the CMS electromagnetic calorimeter consisting of only 7 × 7 PbWO4 crystals read out by photomultipliers, whereas this test used an actual CMS ECAL supermodule. 2. Experimental setup The CMS electromagnetic calorimeter (ECAL) [2], is a homogeneous calorimeter made of scintillating lead tungsten PbWO4 crystals [3]. ∗ for
the CMS Collaboration
0920-5632/$ – see front matter © 2007 Elsevier B.V. All rights reserved. doi:10.1016/j.nuclphysbps.2007.07.015
The central barrel part (EB) consists of 36 supermodules made by 61,200 crystals and is closed by the two endcaps containing 7,324 crystals. Each EB supermodule covers half the barrel length and 20◦ in azimuth. The CMS Hadron Calorimeter (HCAL) [4,5], is designed to measure hadron jets, single hadrons and single muons. In the CMS detector, the central Hadronic Barrel detector (HB) and the Hadronic Endcap detectors (HE) are sampling calorimeters, made of brass and plastic scintillators, and cover the pseudorapidity region of −3 ≤ η ≤ 3. The HB and HE detectors are located inside the 13 m long 4T solenoid magnet. Central shower containment is improved by the Hadronic Outer detector (HO) which is composed of 2 scintillator layers outside the magnet. Forward calorimeters that cover 3 ≤ η ≤ 5 are constructed using quartz fibers in steel absorber and were not part of the 2006 test beam work. In the beam test of 2006, two HB wedges (2 × 20◦ in azimuth), three HO rings (40◦ ), one HE wedge (20◦ ) and one ECAL Barrel supermodule (20◦ ) were mounted on a movable table which enabled us to mimic the directions of particles originating from the LHC interaction point. The H2 beamline was much improved as compared to the previous beam test of 2004, with better particle identification and ability to reject particles produced in beamline interactions.
L. Berntzon / Nuclear Physics B (Proc. Suppl.) 172 (2007) 126–128
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Figure 1. Layout of the H2 beamline in VLE mode. Two beamline configurations were used, for momenta above 10 GeV/c the high energy and for momenta below 10 GeV/c the Very Low Energy (VLE) mode. In order to generate beams with momenta less than 10 GeV/c, a tertiary target (T22) is inserted, and a beamstop was positioned into the high energy section, see Fig. 1. Additional beam focusing and bending elements are used along the VLE path in order to achieve a well defined beam momentum in the range of 1 to 9 GeV/c. Scintillation counters provide trigger and some particle identification information. The trigger signal was created using three scintillation counters, S1(14 × 14 cm2 ) · S2 (4 × 4 cm2 ) · S4(14 × 14 cm2 ). Four large scintillation counters were placed directly after the trigger scintillators and used as beam halo veto. Further scintillation counters were installed between the HB and the HO detectors, as well as behind the HO to identify muons. The beamline was also equipped with Cherenkov counters, time-of-flight detectors and several wire chambers, as shown in Fig. 1. Through the use of Cherenkov threshold, timeof-flight detectors, and the scintillation counters we are able to identify (anti-)protons, kaons, pions, muons and electrons. This beam line is unique, and is particularly well-suited for calorimetry. 3. Preliminary Results The data sets collected include calibration data (for the HCAL using electrons, muons and radioactive source), intercalibration data for the
ECAL, energy scans at both high and low energy, eta and phi scans, crack studies and longitudinal shower profiles of the HB. The relative calibration of each HCAL scintillator was determined using a moving-wire radioactive source. In Fig. 2 the HCAL versus ECAL response to 5 GeV/c π + is shown without any particle identification criteria applied, and in Fig. 3 the remaining events are shown after all π + selection criteria have been applied. 4. Conclusion The features of the ECAL and HCAL response have been measured in detail with different particles and energies. The improved beamline provides various types of particles in the momentum range from 1 to 350 GeV/c. For the first time, we have a complete set of low energy data for electrons, pions, kaons and (anti-)protons for the combined CMS ECAL and HCAL calorimeters. These data are essential to correctly estimate the jet response of the CMS calorimeter system and the detailed analyses are underway. REFERENCES 1. CMS Collaboration, ’The Compact Muon Solenoid Technical Proposal’, CERN/LHCC 94-38, 1994 2. CMS Collaboration, ’The electromagnetic calorimeter project. Technical Design Report’, CERN/LHCC 1997-033, 1997. 3. A. A. Annenkov, P. Lecoq and M. V. Korzik,
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L. Berntzon / Nuclear Physics B (Proc. Suppl.) 172 (2007) 126–128
Figure 2. HCAL vs ECAL response to 5 GeV/c π + is shown before any beam cleaning criteria are applied.
’Lead Tungsten scintillation material’, Nucl. Instr. and Meth. A490 (2002) 30. 4. CMS Collaboration, ’The Hadron Calorimeter Technical Design Report’, CERN/LHCC 1997-032, CMS TDR 3, (1997). 5. S. Abdullin et al. CMS HCAL Collaboration, ’Design, Performance and Calibration of CMS Hadron-Barrel Calorimeter Wedges’, submitted to Nucl. Inst. Meth.
Figure 3. Same as Fig. 2 but all π + selection criteria are applied. Note, for example, the electron contamination is efficiently removed.