The electromagnetic calorimeter for the new muon (g-2) experiment at Fermilab will consist of arrays of PbF2 Cherenkov crystals read out by large-area silicon photo-multiplier (SiPM) sensors. We report here on measurements and simulations using 2.0-4.5 GeV electrons with a 28-element prototype array. All data were obtained using fast waveform digitizers to accurately capture signal pulse shapes vs. energy, impact position, angle, and crystal wrapping. The SiPMs were gain matched using a laser-based calibration system, which also provided a stabilization procedure that allowed gain correction to a level of 10-4 per hour. After accounting for longitudinal fluctuation losses, those crystals wrapped in a white, diffusive wrapping exhibited an energy resolution σ/E of (3.4±0.1)%/E/GeV, while those wrapped in a black, absorptive wrapping had (4.6±0.3)%/E/GeV. The white-wrapped crystals - having nearly twice the total light collection - display a generally wider and impact-position-dependent pulse shape owing to the dynamics of the light propagation, in comparison to the black-wrapped crystals, which have a narrower pulse shape that is insensitive to impact position.
|Number of pages||10|
|Journal||Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment|
|State||Published - May 21 2015|
Bibliographical noteFunding Information:
We thank Adam Para for the initial suggestion to test PbF 2 as a candidate material and for excellent advice on evaluating and choosing SiPM products. Tianchi Zhao negotiated the original contract with SICCAS and helped evaluate early samples. Carsten Hast, Keith Jobe and Zenon Szalata hosted this effort at the SLAC ESTB facility, which is supported under Department of Energy (DOE) contract DE-AC02-76SF00515 . This research was supported by the National Science Foundation (NSF) MRI program ( PHY-1337542 ), by the DOE Offices of Nuclear ( DE-FG02-97ER41020 ) and High-Energy Physics ( DE-SC0008037 ), by the NSF Physics Division ( PHY-1205792 , PHY-1307328 , PHY-1307196 , DGE-1144153 ), by the Istituto Nazionale di Fisica Nucleare (Italy) , and by the National Natural Science Foundation of China ( 11375115 ) and the Shanghai Pujiang Program ( 13PJ1404200 ).
© 2015 Elsevier B.V. All rights reserved.
- Electromagnetic calorimeter
- Lead-fluoride crystals
- Silicon photomultiplier
ASJC Scopus subject areas
- Nuclear and High Energy Physics