N3B2  Photodetectors 2

Wednesday, Nov. 4  10:30-12:30  San Diego

Session Chair:  Etiennette Auffray, CERN, Switzerland; Dennis Schaart, Delft University of Technology, Netherlands

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(10:30) N3B2-1, Functional Characterization of RGB-HD and NUV-HD FBK Silicon Photomultipliers from 300 K to 60 K

A. Gola1, F. Acerbi1, A. Ferri1, G. Korga2, G. Paternoster1, C. Piemonte1, A. Razeto3, V. Regazzoni1, D. Sablone3, N. Zorzi1

1Fondazione Bruno Kessler, Trento, Italy
2Houston University, Houston, Texas, USA
3Laboratori Nazionali del Gran Sasso, Assergi, Italy
We carried out the cryogenic characterization of the two most recent SiPM technologies developed at Fondazione Bruno Kessler (FBK), the RGB-HD and the NUV-HD. We tested SiPMs with a cell size of 25 µm. At room temperature, the peak photon detection efficiency (PDE) was 48% at 550 nm and 9 V over-voltage for the RGB-HD and 50% at 410 nm and 7 V for the NUV-HD. We measured the main SiPM characteristics, including the primary, Poisson-distributed, dark count rate (DCR), the optical crosstalk and the afterpulsing, from 330 K to 65 K. We showed that the devices worked up to 7 V over-voltage at cryogenic temperatures, without any change of the PDE. The DCR was well below the measurement limit of our setup, which is currently 100 Hz/mm2. Among other effects, we observed a notable increase of afterpulsing below 200 K in both technologies. The increase of the value of the polysilicon quenching resistor was an important factor in limiting the afterpulsing probability of NUV-HD SiPMs to 40% at 65 K and 7 V over-voltage. Finally, we characterized at 77 K an 8x8, RGB-HD, SiPM array with a 4 mm pitch, having a total active area of 10 cm2. Thanks to the excellent SiPM gain uniformity and to the low DCR, we were able to demonstrate single-photon resolution, reading the whole array with a single electronic channel. These measurements should be considered preliminary studies to use very large SiPM arrays for the detection of the light emitted by liquid scintillators (Argon or Xenon), such as in the future DarkSide experiments.

(10:49) N3B2-2, (Withdrawn), Characterization of SiPM Properties at Cryogenic Temperatures

P. Achenbach1, M. Biroth1, A. Thomas1, E. Downie2

1Johannes Gutenberg-University, Institute for Nuclear Physics, Mainz, Germany
2George Washington University, Dept. of Physics, Washington, DC, USA
Abstract withdrawn

(10:50) N3B2-3, Performance of Several Solid State Photomultipliers with CLYC Scintillator

K. E. Mesick1, L. C. Stonehill1, J. T. Morrell2, D. D. S. Coupland1

1ISR-1, Los Alamos National Laboratory, Los Alamos, NM, USA
2Massachusetts Institute of Technology, Cambridge, MA, USA
Cs2LiYCl6:Ce3+ (CLYC) is an inorganic scintillator that has recently garnered attention for its ability to detect and discriminate between gammas and thermal neutrons. While scintillators are typically coupled to traditional photomultiplier tubes (PMTs) for data acquisition, this setup may not be feasible in all applications. Solid state photomultipliers (SSPMs) offer potential advantages including smaller size, lower voltage requirements, added robustness, and imperviousness to magnetic fields. We investigate several important performance parameters of three different solid state photomultipliers when reading out CLYC crystals: energy resolution, pulse shape and discrimination ability, and linearity. These performance parameters are assessed at a variety of temperatures between -20°C and +50°C.

(11:10) N3B2-4, Very Large Area 20cm X 20cm Flat Panel Phototubes Using ALD Microchannel Plates

O. H. W. Siegmund1, C. D. Ertley1, S. R. Jelinsky1, J. B. McPhate1, J. Tedesco1, M. J. Minot2, A. O'Mahony2, C. A. Craven2

1Space Sciences Laboratory, University of California, Berkeley, Berkeley, CA, USA
2Incom Inc., Charlton, MA, USA
Micro-capillary arrays have been functionalized using atomic layer deposition (ALD) to produce large area microchannel plates (MCPs) for detectors with cross delay line and strip line readouts. Using low cost borosilicate micro-capillary substrates has advantages over traditional MCPs, including the ability to be produced in large formats (20cm), low intrinsic background (7 C cm-2 charge extraction after preconditioning (vacuum bake and burn-in). Results with 20 cm open face detectors have shown the gain, pulse height distribution, imaging performance, and background are equivalent, or better than conventional MCPs. These novel MCPs have also been used to build large area (20 cm × 20 cm) sealed tube detectors. Design and fabrication of a 20 cm sealed tube assembly comprises of a borosilicate entrance window, a proximity focused bialkali photocathode, a pair of ALD MCPs and a strip-line readout anode. Two designs have been explored, a brazed ceramic walled enclosure and an all borosilicate glass enclosure, both with an indium seal. We have achieved >20% quantum efficiency and good gain uniformity over the whole detector and obtained event timing accuracy of <200ps FWHM.

(11:30) N3B2-5, Testing and Performances of 6 Cm × 6 Cm MCP-Based Photodetectors

J. Wang

High Energy Physics, Argonne National Laboratory, Lemont, United States

On behalf of the Argonne MCP Photodetector Group
Micro-channel plate (MCP)-based photodetectors feature picosecond level time resolution, sub-mm level position resolution and high rate capability. These excellent performances make them a perfect candidate for the next generation large area photodetectors to replace the traditional Photomultipliers (PMTs). The large-area picosecond photodetector (LAPPD) collaboration is currently developing large-area photodetectors based on Atomic Layer Deposition (ALD) functionalized MCPs and low cost glass packaging technology. Recently, we constructed a Small Tile Processing System (STPS) at Argonne National Laboratory (ANL), for producing small form factor, 6 cm × 6 cm, glass-body photodetectors. We have successfully demonstrated techniques to make a reliable indium seal and maintain the ultra-high vacuum inside the photodetector. Here we report the successful fabrication of a series of fully processed and hermetically sealed photodetectors with glass packaging, reaching the milestone of producing the first long-lived functional devices for the LAPPD project. The performances of these prototypes were characterized with a pulsed laser test facility at ANL. We have measured a gain of up to 107, single photoelectron time resolution of 57 ps, multi-photoelectron time resolution of 15 ps, position resolution better than 1 mm, and rate capability higher than 1 MHz/cm2. The position scan shows a uniformity of less than 30%. In this paper, we present the small tile processing system, the detector assembly, experimental setup, and the key performances. At present, we are working on the detector optimization, based on an independently biased HV connection. Recent progress will also be presented.

(11:50) N3B2-6, Sensing an Electron Cloud Emanating from a Microchannel Plate Stack

R. T. deSouza, B. B. Wiggins, D. Siwal

Center for Exploration of Energy and Matter/Department of Chemistry, Indiana University, Bloomington, Indiana, USA
Microchannel plates (MCPs) are routinely used in the detection of photons, electrons, and ions. Due to their high amplification and excellent timing characteristics they are particularly useful in the detection of a single photon, electron, or ion. In addition to sub-nanosecond time resolution, MCP detectors can also provide position resolution making them useful in imaging applications. In the described approach, the position of the incident particle is determined by sensing the electron cloud as it emanates from a MCP stack. The bipolar nature of the induced signals provides a particularly unique signal. By coupling a sense wire plane to a delay line a position resolution of 466 µm has been achieved. A setup to characterize the dependence of the induced signals on the position and magnitude of the electron cloud, through an independent measurement of its position, is presented. A second generation prototype detector which employs a differential approach is also described.