- Email: [email protected]
Preliminary performance results for the ATLAS RPC test stand in Lecce
ARTICLE IN PRESS
Nuclear Instruments and Methods in Physics Research A 572 (2007) 18–19 www.elsevier.com/locate/nima
Preliminary performance results for the ATLAS RPC test stand in Lecce M. Biancoa,b,, G. Chiodinib, E. Gorinia,b, F. Grancagnolob, R. Perrinob, M. Primaverab, S. Spagnoloa,b a
Dip. di Fisica, Universita´ degli Studi di Lecce, via Arnesano, 73100 Lecce, Italy b INFN, Sezione di Lecce, via Arnesano, 73100 Lecce, Italy Available online 13 November 2006
Abstract We present here a preliminary performance analysis of the ATLAS RPC tested at the Lecce cosmic ray testing facility. In this paper we define the operating working point for our detectors and show the distribution of the principal operating parameters. r 2006 Elsevier B.V. All rights reserved. PACS: 29.40.Cs Keywords: RPC; ATLAS
1. Introduction Resistive Plate Chambers (RPC) [1] have been chosen as the muon trigger detectors for the ATLAS experiment barrel region. In order to ensure the proper operation of each assembled unit, a detailed procedure made of several tests was performed at three different cosmic ray test stands. One of this was set up at the Lecce INFN & Physics Department HEP Laboratory [2]. Since July 2004 to February 2006, 380 different units have been certified at Lecce Test Stand, in particular all 198 ATLAS Barrel Outer Small Chambers (BOS) [3]. The performance analysis reported here refers to this particular sample. All quantities have been plotted as a function of pressure and temperature corrected high voltage (effective voltage) HV eff ¼ HV app T=T 0 P0 =P where T 0 ¼ 293:15 K and P0 ¼ 1013 mbar [4]. From data, best fit parameters are extracted and saved in a database for record. 2. Gas volume efficiency and working point determination RPC efficiency has been measured as a function of the effective high voltage. The efficiency curves have been Corresponding author. INFN, Sezione di Lecce, via Arnesano, 73100 Lecce, Italy. E-mail address: [email protected] (M. Bianco).
0168-9002/$ - see front matter r 2006 Elsevier B.V. All rights reserved. doi:10.1016/j.nima.2006.10.158
obtained for all gas volumes and relative strip panels. The resulting average value for gap efficiency is 0:984 0:004 (Fig.1). Only five gas volumes have an efficiency lower than 97%. Gas volumes with efficiency lower than 0:965 were rejected and replaced. We define the Working Point (WP) as 100 V over the effective HV at which the efficiency is 97:5% of the top value. We then extract from our data the singles rate (noise), cluster size, and other quantities at WP using our fitted curves. At the WP the strip panel efficiency is 0:956 0:013 due to the presence of some dead channels in the electronics. The electronics efficiency has been evaluated to be 0:988 0:010.
2.1. Cluster size, noise and gap current Cluster size, noise and gap current are strongly dependent on the applied high voltage. For the chosen WP the average cluster size is about 1.5. The single rate, measured for each of the strip panel, is found to depend on the operating temperature. In fact, since the test was performed over a long period of time, our data have been taken in a large range of temperatures (19.5 to 29 1C). The temperature averaged noise for the ATLAS BOS is about 1 Hz=cm2 . The gap current at WP is also strongly dependent on the operating temperature, mainly due to change in inner surface electrode quality and resistivity [5].
ARTICLE IN PRESS M. Bianco et al. / Nuclear Instruments and Methods in Physics Research A 572 (2007) 18–19
19
3. Conclusions At the Lecce Test Stand 380 ATLAS RPC units have been tested and have been shipped to CERN to be installed on the detector after being certified to satisfy the ATLAS requirements. A preliminary study on the performances of the 198 BOS chambers has been reported. A complete and more detailed analysis to characterize the detectors is in progress, with a particular emphasis on its behavior with temperature.
References
Fig. 1. Gas Volume plateau efficiency distribution.
It in fact grows up with the temperature, and its average value is 0:5 mA=m2 .
[1] R. Santonico, R. Cardarelli, Nucl. Instr. and Meth. A 187 (1981) 377. [2] M. Bianco, et al., Nucl. Instr. and Meth. A 565 (2006) 450. [3] ATLAS Collaboration, ATLAS Muon Spectrometer Technical Design Report, CERN/LHCC/97-22, ATLAS TDR 10, 1997. [4] M. Abbrescia, et al., Nucl. Instr. and Meth. A 359 (1995). [5] G. Chiodini, et al., see proceedings at this conference.
Nuclear Instruments and Methods in Physics Research A 572 (2007) 18–19 www.elsevier.com/locate/nima
Preliminary performance results for the ATLAS RPC test stand in Lecce M. Biancoa,b,, G. Chiodinib, E. Gorinia,b, F. Grancagnolob, R. Perrinob, M. Primaverab, S. Spagnoloa,b a
Dip. di Fisica, Universita´ degli Studi di Lecce, via Arnesano, 73100 Lecce, Italy b INFN, Sezione di Lecce, via Arnesano, 73100 Lecce, Italy Available online 13 November 2006
Abstract We present here a preliminary performance analysis of the ATLAS RPC tested at the Lecce cosmic ray testing facility. In this paper we define the operating working point for our detectors and show the distribution of the principal operating parameters. r 2006 Elsevier B.V. All rights reserved. PACS: 29.40.Cs Keywords: RPC; ATLAS
1. Introduction Resistive Plate Chambers (RPC) [1] have been chosen as the muon trigger detectors for the ATLAS experiment barrel region. In order to ensure the proper operation of each assembled unit, a detailed procedure made of several tests was performed at three different cosmic ray test stands. One of this was set up at the Lecce INFN & Physics Department HEP Laboratory [2]. Since July 2004 to February 2006, 380 different units have been certified at Lecce Test Stand, in particular all 198 ATLAS Barrel Outer Small Chambers (BOS) [3]. The performance analysis reported here refers to this particular sample. All quantities have been plotted as a function of pressure and temperature corrected high voltage (effective voltage) HV eff ¼ HV app T=T 0 P0 =P where T 0 ¼ 293:15 K and P0 ¼ 1013 mbar [4]. From data, best fit parameters are extracted and saved in a database for record. 2. Gas volume efficiency and working point determination RPC efficiency has been measured as a function of the effective high voltage. The efficiency curves have been Corresponding author. INFN, Sezione di Lecce, via Arnesano, 73100 Lecce, Italy. E-mail address: [email protected] (M. Bianco).
0168-9002/$ - see front matter r 2006 Elsevier B.V. All rights reserved. doi:10.1016/j.nima.2006.10.158
obtained for all gas volumes and relative strip panels. The resulting average value for gap efficiency is 0:984 0:004 (Fig.1). Only five gas volumes have an efficiency lower than 97%. Gas volumes with efficiency lower than 0:965 were rejected and replaced. We define the Working Point (WP) as 100 V over the effective HV at which the efficiency is 97:5% of the top value. We then extract from our data the singles rate (noise), cluster size, and other quantities at WP using our fitted curves. At the WP the strip panel efficiency is 0:956 0:013 due to the presence of some dead channels in the electronics. The electronics efficiency has been evaluated to be 0:988 0:010.
2.1. Cluster size, noise and gap current Cluster size, noise and gap current are strongly dependent on the applied high voltage. For the chosen WP the average cluster size is about 1.5. The single rate, measured for each of the strip panel, is found to depend on the operating temperature. In fact, since the test was performed over a long period of time, our data have been taken in a large range of temperatures (19.5 to 29 1C). The temperature averaged noise for the ATLAS BOS is about 1 Hz=cm2 . The gap current at WP is also strongly dependent on the operating temperature, mainly due to change in inner surface electrode quality and resistivity [5].
ARTICLE IN PRESS M. Bianco et al. / Nuclear Instruments and Methods in Physics Research A 572 (2007) 18–19
19
3. Conclusions At the Lecce Test Stand 380 ATLAS RPC units have been tested and have been shipped to CERN to be installed on the detector after being certified to satisfy the ATLAS requirements. A preliminary study on the performances of the 198 BOS chambers has been reported. A complete and more detailed analysis to characterize the detectors is in progress, with a particular emphasis on its behavior with temperature.
References
Fig. 1. Gas Volume plateau efficiency distribution.
It in fact grows up with the temperature, and its average value is 0:5 mA=m2 .
[1] R. Santonico, R. Cardarelli, Nucl. Instr. and Meth. A 187 (1981) 377. [2] M. Bianco, et al., Nucl. Instr. and Meth. A 565 (2006) 450. [3] ATLAS Collaboration, ATLAS Muon Spectrometer Technical Design Report, CERN/LHCC/97-22, ATLAS TDR 10, 1997. [4] M. Abbrescia, et al., Nucl. Instr. and Meth. A 359 (1995). [5] G. Chiodini, et al., see proceedings at this conference.