A current mode detector array for γ ray asymmetry measurements

M. T. Gericke; C. Blessinger; J. D. Bowman; R. C. Gillis; J. Hartfield; T. Ino; M. Leuschner; Y. Masuda; G. S. Mitchell; S. Muto; H. Nann; S. A. Page; S. I. Penttilä; W. D. Ramsay; P. N. Seo; W. M. Snow; J. Tasson; W. S. Wilburn

doi:10.1016/j.nima.2004.11.043

A current mode detector array for γ ray asymmetry measurements

M. T. Gericke, C. Blessinger, J. D. Bowman, R. C. Gillis, J. Hartfield, T. Ino, M. Leuschner, Y. Masuda, G. S. Mitchell, S. Muto, H. Nann, S. A. Page, S. I. Penttilä, W. D. Ramsay, P. N. Seo, W. M. Snow, J. Tasson, W. S. Wilburn

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23 Scopus citations

Abstract

We have built a CsI(Tl) γ-ray detector array for the NPDGamma experiment to search for a small parity-violating directional asymmetry in the angular distribution of 2.2 MeV γ-rays from the capture of polarized cold neutrons by protons with a sensitivity of several ppb. The weak pion-nucleon coupling constant can be determined from this asymmetry. The small size of the asymmetry requires a high cold neutron flux, control of systematic errors at the ppb level, and the use of current mode γ-ray detection with vacuum photodiodes and low-noise solid-state preamplifiers. The average detector photoelectron yield was determined to be 1300 photoelectrons per MeV. The RMS width seen in the measurement is therefore dominated by the fluctuations in the number of γ-rays absorbed in the detector (counting statistics) rather than the intrinsic detector noise. The detectors were tested for noise performance, sensitivity to magnetic fields, pedestal stability and cosmic background. False asymmetries due to gain changes and electronic pickup in the detector system were measured to be consistent with zero to an accuracy of 10-9 in a few hours. We report on the design, operating criteria, and the results of measurements performed to test the detector array.

Original language	English
Pages (from-to)	328-347
Number of pages	20
Journal	Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment
Volume	540
Issue number	2-3
DOIs	https://doi.org/10.1016/j.nima.2004.11.043
State	Published - Mar 21 2005
Externally published	Yes

Funding

The authors would like to thank Mr. G. Peralta (LANL) for his technical support during this experiment, Mr. W. Fox (IUCF) and Mr. T. Ries (TRIUMF) for the mechanical design of the array and the construction of the stand and Mr. M. Kusner of Saint-Gobain in Newbury, Ohio for interactions during the manufacture and characterization of the CsI(Tl) crystals. We would also like to thank TRIUMF for providing the personnel and infrastructure for the stand construction. This work was supported in part by the US Department of Energy (Office of Energy Research, under Contract W-7405-ENG-36), the National Science Foundation (Grant No. PHY-0100348) and the NSF Major Research Instrumentation program (NSF-0116146), the Natural Sciences and Engineering Research Council of Canada and the Japanese Grant-in-Aid for Scientific Research A12304014.

Keywords

CsI detector array
Current mode
Parity violation
Radiative neutron capture
Shot noise
γ detector

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10.1016/j.nima.2004.11.043

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Gericke, M. T., Blessinger, C., Bowman, J. D., Gillis, R. C., Hartfield, J., Ino, T., Leuschner, M., Masuda, Y., Mitchell, G. S., Muto, S., Nann, H., Page, S. A., Penttilä, S. I., Ramsay, W. D., Seo, P. N., Snow, W. M., Tasson, J., & Wilburn, W. S. (2005). A current mode detector array for γ ray asymmetry measurements. Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 540(2-3), 328-347. https://doi.org/10.1016/j.nima.2004.11.043

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title = "A current mode detector array for γ ray asymmetry measurements",

abstract = "We have built a CsI(Tl) γ-ray detector array for the NPDGamma experiment to search for a small parity-violating directional asymmetry in the angular distribution of 2.2 MeV γ-rays from the capture of polarized cold neutrons by protons with a sensitivity of several ppb. The weak pion-nucleon coupling constant can be determined from this asymmetry. The small size of the asymmetry requires a high cold neutron flux, control of systematic errors at the ppb level, and the use of current mode γ-ray detection with vacuum photodiodes and low-noise solid-state preamplifiers. The average detector photoelectron yield was determined to be 1300 photoelectrons per MeV. The RMS width seen in the measurement is therefore dominated by the fluctuations in the number of γ-rays absorbed in the detector (counting statistics) rather than the intrinsic detector noise. The detectors were tested for noise performance, sensitivity to magnetic fields, pedestal stability and cosmic background. False asymmetries due to gain changes and electronic pickup in the detector system were measured to be consistent with zero to an accuracy of 10-9 in a few hours. We report on the design, operating criteria, and the results of measurements performed to test the detector array.",

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author = "Gericke, {M. T.} and C. Blessinger and Bowman, {J. D.} and Gillis, {R. C.} and J. Hartfield and T. Ino and M. Leuschner and Y. Masuda and Mitchell, {G. S.} and S. Muto and H. Nann and Page, {S. A.} and Penttil{\"a}, {S. I.} and Ramsay, {W. D.} and Seo, {P. N.} and Snow, {W. M.} and J. Tasson and Wilburn, {W. S.}",

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doi = "10.1016/j.nima.2004.11.043",

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Gericke, MT, Blessinger, C, Bowman, JD, Gillis, RC, Hartfield, J, Ino, T, Leuschner, M, Masuda, Y, Mitchell, GS, Muto, S, Nann, H, Page, SA, Penttilä, SI, Ramsay, WD, Seo, PN, Snow, WM, Tasson, J & Wilburn, WS 2005, 'A current mode detector array for γ ray asymmetry measurements', Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, vol. 540, no. 2-3, pp. 328-347. https://doi.org/10.1016/j.nima.2004.11.043

TY - JOUR

T1 - A current mode detector array for γ ray asymmetry measurements

AU - Gericke, M. T.

AU - Blessinger, C.

AU - Bowman, J. D.

AU - Gillis, R. C.

AU - Hartfield, J.

AU - Ino, T.

AU - Leuschner, M.

AU - Masuda, Y.

AU - Mitchell, G. S.

AU - Muto, S.

AU - Nann, H.

AU - Page, S. A.

AU - Penttilä, S. I.

AU - Ramsay, W. D.

AU - Seo, P. N.

AU - Snow, W. M.

AU - Tasson, J.

AU - Wilburn, W. S.

PY - 2005/3/21

Y1 - 2005/3/21

N2 - We have built a CsI(Tl) γ-ray detector array for the NPDGamma experiment to search for a small parity-violating directional asymmetry in the angular distribution of 2.2 MeV γ-rays from the capture of polarized cold neutrons by protons with a sensitivity of several ppb. The weak pion-nucleon coupling constant can be determined from this asymmetry. The small size of the asymmetry requires a high cold neutron flux, control of systematic errors at the ppb level, and the use of current mode γ-ray detection with vacuum photodiodes and low-noise solid-state preamplifiers. The average detector photoelectron yield was determined to be 1300 photoelectrons per MeV. The RMS width seen in the measurement is therefore dominated by the fluctuations in the number of γ-rays absorbed in the detector (counting statistics) rather than the intrinsic detector noise. The detectors were tested for noise performance, sensitivity to magnetic fields, pedestal stability and cosmic background. False asymmetries due to gain changes and electronic pickup in the detector system were measured to be consistent with zero to an accuracy of 10-9 in a few hours. We report on the design, operating criteria, and the results of measurements performed to test the detector array.

AB - We have built a CsI(Tl) γ-ray detector array for the NPDGamma experiment to search for a small parity-violating directional asymmetry in the angular distribution of 2.2 MeV γ-rays from the capture of polarized cold neutrons by protons with a sensitivity of several ppb. The weak pion-nucleon coupling constant can be determined from this asymmetry. The small size of the asymmetry requires a high cold neutron flux, control of systematic errors at the ppb level, and the use of current mode γ-ray detection with vacuum photodiodes and low-noise solid-state preamplifiers. The average detector photoelectron yield was determined to be 1300 photoelectrons per MeV. The RMS width seen in the measurement is therefore dominated by the fluctuations in the number of γ-rays absorbed in the detector (counting statistics) rather than the intrinsic detector noise. The detectors were tested for noise performance, sensitivity to magnetic fields, pedestal stability and cosmic background. False asymmetries due to gain changes and electronic pickup in the detector system were measured to be consistent with zero to an accuracy of 10-9 in a few hours. We report on the design, operating criteria, and the results of measurements performed to test the detector array.

KW - CsI detector array

KW - Current mode

KW - Parity violation

KW - Radiative neutron capture

KW - Shot noise

KW - γ detector

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DO - 10.1016/j.nima.2004.11.043

M3 - Article

AN - SCOPUS:20244367150

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SP - 328

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JO - Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment

JF - Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment

IS - 2-3

ER -

A current mode detector array for γ ray asymmetry measurements

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Keywords

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