Please note! All times in the online program are given in New York - America (GMT -04:00) times!

New York - America ()
Jan 29, 2022, 8:17:03 AM
Your time ()
Tokyo - Asia ()
Jan 29, 2022, 10:17:03 PM
Our exhibitors and sponsors – click on name to visit booth:

To search for a specific ID please enter the hash sign followed by the ID number (e.g. #123).

Photodetectors I

Session chair: Cardini , Alessandro (INFN - Istituto Nazionale di Fisica Nucleare, Sezione di Cagliari, Monserrato, Italy); Ariño-Estrada , Gerard (University of California, Davis, Department of Biomedical Engineering, Davis, USA)
Shortcut: N-22
Date: Thursday, 21 October, 2021, 7:00 AM - 8:45 AM
Room: NSS - 2
Session type: NSS Session


Click on an contribution to preview the abstract content.

7:00 AM N-22-01

Capacitively Coupled LAPPDs with 2D Pixelated Readout Planes for Time of Flight and Ring Imaging Cherenkov Applications (#1292)

A. Kiselev1, B. Azmoun1, M. Chiu1, K. Dehmelt2, A. Deshpande2, P. Garg2, X. He4, T. Hemmick2, M. L. Purschke1, M. Sarsour4, C. Woody1, J. Xie3, M. Alfred6, A. Holt6, C. Scarlett5, S. Nelson5, L. Mwibanda5, A. Alsayegh5, R. Alrashidi5, S. Kuudaar5, M. Harvey7, M. Minot8, M. Popecki8, S. Butler8, M. Foley8, A. Lyashenko8, T. Cremer8, C. Hamel8, P. Whitney8, M. Aviles8, M. Stochaj8, C. Walne8

1 Brookhaven National Laboratory, Upton, New York, United States of America
2 Stony Brook University, Stony Brook, New York, United States of America
3 Argonne National Laboratory, Lemont, Illinois, United States of America
4 Georgia State University, Atlanta, Georgia, United States of America
5 Florida A&M University, Tallahassee, Florida, United States of America
6 Howard University, Washington, United States of America
7 Texas Southern University, Houston, Texas, United States of America
8 Incom Inc., Charlton, Massachusetts, United States of America


Large Area Picosecond Photodetectors (LAPPDs) are micro-channel based photosensors featuring hundreds of square centimeters of sensitive area in a single package and timing resolution on the order of 50 ps for a single photon detection.  However, LAPPDs currently do not exist in finely pixelated 2D readout configurations that in addition to the high-resolution timing would also provide the high spatial resolution required for Ring Imaging CHerenkov (RICH) detectors. One of the recent LAPPD models, the so-called Gen II LAPPD, provides the opportunity to overcome the lack of pixellation in a relatively straightforward way. The readout plane of Gen II LAPPD is external to the sealed detector itself. It is a conventional inexpensive capacitively coupled printed circuit board (PCB) that can be laid out in a custom application-specific way for 1D or 2D sensitive area pixellation. This allows for a much shorter readout-plane prototyping cycle and provides unprecedented flexibility in choosing an appropriate segmentation that then could be optimized for any particular detector needs in terms of pad size, orientation, and shape. We fully exploit this feature by designing and testing a variety of readout PCBs with interleaved anode designs. Our main goal is to identify optimal anode geometries that would yield high resolution measurement of Cherenkov photon impact points in a RICH detector focal plane, consequently improved ring diameter determination and e/p/K/p separation for the purposes of Particle Identification (PID), but at the same time preserve intrinsic timing resolution of these photosensors. Preliminary data acquired in the lab will be shown using a laser system to probe the response of several interleaved and standard pixelated patterns. However, more extensive results from a beam test will be presented at the conference with a broader survey of interleaved anodes.

Keywords: LAPPD, RICH, PID
7:15 AM N-22-02

Study of Optimal Segmentation for Active Hybrid Single-Photon Sensors (#972)

R. Manera1, S. Gomez1, M. Cambell2, J. M. Fernández-Tenllado2, J. Mauricio1, D. Sánchez1, N. Egidos2, F. N. Bandi3, R. Ballabriga2, D. Gascón1

1 University of Barcelona, Institute of Cosmos Sciences (ICCUB), Barcelona, Spain
2 CERN, Microelectronics Section, Geneva, Genève, Switzerland
3 Microelectronics Institute of Sevilla (IMSE-CNM), Sevilla, Spain


FastICpix is a novel reconfigurable low light-level hybrid detector concept that can be scaled to arbitrarily large areas and that aims to measure the position and the time of arrival of single photons with ~20 ps time resolution, bringing a revolution in medical imaging and other Time-of-Flight applications. FastICPix consists of an array of groups of SPADs 3D-connected to a pixelated readout ASIC based on novel reconfigurable architectures designed in 65 nm CMOS technology. Two flavours of front-end amplifiers have been tested, achieving picosencond jitter. FastICpix concept has been validated by simulation.

AcknowledgmentThis work has been supported by the ATTRACT project funded by the EC under Grant agreement 777222.
Keywords: Silicon Photomultiplier, Single Photon Time Resolution, SPAD, photo-detector technology, Fast Front-end electronics.
7:30 AM N-22-03

Highly pixelated microchannel plate photodetector with precision timing for radiation detection (#1410)

J. Xie1, Z. - E. Meziani1, D. Walters1, L. Xia1

1 Argonne National Laboratory, Lemont, Illinois, United States of America


Microchannel plate (MCP) photodetectors have attracted considerable interests due to their compact size, high gain, exceptional timing and spatial resolutions. The recent success of low-cost MCPs based on micron-sized glass capillary array (GCA) and atomic layer deposition (ALD) techniques reduced the unit price an order of magnitude lower, making it affordable for many applications ranging from charged-particle detection to photon counting, imaging, and night vision.

We report a detailed design, fabrication, and characterization of highly pixelated MCP photodetector with precision timing based on state-of-the-art ALD-coated MCPs. The MCP photodetector was designed with low-cost borosilicate glass envelope and hermetically sealed with a bialkali photocathode in a vacuum. The fabrication process consists of multiple steps including GCA functionalization through ALD, MCP baking and scrubbing, photocathode deposition, and hermetic thermo-compression sealing. With smaller pore size (10 µm) MCPs, the prototype MCP photodetector exhibits electron gain well beyond 107 level with good uniformity, an excellent rise time of 394 ps, full width at half maximum (FWHM) of 649 ps, and transit time resolution of 35 ps.

A pixelated readout scheme was tested in an MCP vacuum chamber mimicking MCP photodetector operation, the result shows acceptable cross talk with position resolution of 0.8 mm with 4 mm × 4 mm pixel size. Integration of the pixelated readout into device fabrication is on-going and device test results will be reported. Moreover, we have designed a 10 × 10 cm2 MCP photodetector fabrication facility to bring the device into a more practical size for radiation detector prototypes, the status of the new facility will also be reported.


This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics, and Office of High Energy Physics under contract number DE-AC02-06CH11357 and DE-SC0018445.

Keywords: Photodetector, Microchannel Plate, Precision timing
7:45 AM N-22-04

Long term aging tests of the new PMTs for the HL-LHC ATLAS hadron calorimeter upgrade (#212)

S. Silverstein1, G. Di Gregorio2

1 Stockholm University, Department of Physics, Stockholm, Sweden
2 INFN, University of Pisa, Pisa, Italy

On behalf of the ATLAS Tile Calorimeter collaboration


The central hadronic Tile calorimeter (TileCal) of the ATLAS experiment, is read out by approximately 10,000 photomultipliers (PMT). Earlier PMT performance test results have shown a degradation in response due to the integrated anode charge, with projected losses exceeding 25% for approximately 8% of the photomultipliers, corresponding to the most-exposed TileCal cells, which are expected to integrate charges up to 600 C over the High-Luminosity Large Hadron Collider program. To maintain performance, these photomultipliers will be substituted with a newer version. A local test bench In the Pisa laboratory is being used to study the performance of the new photomultipliers after integration of anode charges exceeding 300 C. The new photomultiplier model has been tested for the first time after integrating more than 100 C of anode charge. Preliminary results obtained in the Pisa laboratory are shown.

Keywords: PMT, aging, atlas, LHC
8:00 AM N-22-05

Performance of the 50 cm Photomultiplier Tube for Hyper-Kamiokande (#657)

Y. Maekawa1, C. Fujisawa1, Y. Nishimura1

1 Keio University, Faculty of Science and Technology, Yokohama, Japan

On behalf of the Hyper-Kamiokande Collaboration


We developed a 50 cm-diameter photomultiplier tube (PMT) for Hyper-Kamiokande, which is a large water Cherenkov detector in Japan aiming at neutrino and nucleon-decay research by forty thousand photosensors. The PMT, R12860 manufactured by Hamamatsu Photonics K.K. (Hamamatsu), achieved a double detection efficiency, reduced timing and charge resolutions and sufficient mechanical strength compared with a prior 50 cm PMT, R3600 for Super-Kamiokande. In 2018 over a hundred of the R12860 PMTs were installed in Super-Kamiokande, where we evaluated the performance together with the R3600 PMTs.  The collection efficiency reached 95% with a higher quantum efficiency (QE) of 32% typical at peak of wavelength around 400 nm than 22% QE in case of the Super-Kamiokande.  Charge resolutions were evaluated to be 27% in standard deviation and time resolutions to be 1.5 nanoseconds in FWHM. Recently noise reduction succeeded with a clean materials and low dark count rate. The Hyper-Kamiokande construction and the PMT production started since 2020 for the operation start from 2027. Details of the performance and design for the improved 50 cm PMT will be reported.

Keywords: Photodetectors, Neutrino, Water Cherenkov Detector
8:15 AM N-22-06

Novel Thin Film Growth Techniques for Bi-Alkali Photocathodes (#1102)

H. Bhandari1, O. Maksimov1, V. Nagarkar1, J. Smedley2, M. Gaowei3, A. Lyashenko4

1 Radiation Monitoring Devices Inc., Watertown, Massachusetts, United States of America
2 LANL, Los Alamos, New Mexico, United States of America
3 BNL, Upton, New York, United States of America
4 Incom Inc., Charlton, Massachusetts, United States of America


Photoinjectors for accelerators and scintillation photodetectors require photocathodes with high quantum efficiency (QE) and long lifetime. Bi-alkali antimonide photocathodes, such as K2CsSb and Na2KSb, have been a subject of active research for more than 70 years because of its relatively high QE (~20-30%) and a good spectral match with the emissions of gamma, x-ray and neutron scintillators. Any major advances in the cathode QE will directly impact the spectroscopic energy resolution of the currently-used scintillators. While the photoemission theory predicts a far higher QE (> 100%) than what the industry has realized, it is only recently that the modern synchrotron techniques have shed light on the limitation of the current cathode growth techniques. Such analysis has led to the understanding that the traditional growth process for cathodes result in poor uniformity in thickness, stoichiometry, crystal structure and a rough surface morphology. This limits the realization of the full potential for the bi-alkali cathodes.
In this paper, we report on novel thin-film techniques, such as sputter deposition, pulsed laser deposition (PLD) and thermal co-evaporation, for the bi-alkali cathodes. These growth techniques owe their success to the recent innovation for synthesizing bulk bi-alkali compounds. The cathodes grown using the bulk "targets" have demonstrated a peak QE> 20% at this early stage of research. Cathodes grown by sputtering have one of the smoothest surface morphologies of <1 nm RMS, which demonstrate potential for photocathodes for the next-generation Linac Coherent Light Source (LCLS) II that requires low beam emittance. Cathodes by thermal co-evaporation can be grown in less than 5 mins covering a large surface area up to 8” tiles, making it conducive for economic manufacturing of photodetectors.


This work has been supported by DOE contracts DE-SC0017202, DE-SC0017694, and DE-SC0019927

Keywords: Photocathodes, Photomultiplier tubes, Photoinjectors, bi-alkali antimonide, LAPPD
8:30 AM N-22-07

Development of Silicon PIN Photodiode for X-ray Detection (#326)

J. Baek1, S. Hwang2, H. Hyun2, H. Jang2, J. Kim1, S. Kim2, S. Lee1, H. Park1

1 Kyungpook National University, Department of Physics, Daegu, Republic of Korea
2 Pohang Accelerator Laboratory, XFEL Beamline Division, Pohang, Republic of Korea


For X-ray detection devices, silicon PIN photodiode  (PD) is widely used. We developed a silicon PIN PD, so-called “PAL-PD”, using a 500 µm thickness n-type high resistivity silicon wafer. It has 1 cm × 1 cm size because this size is widely used in X-ray diagnostics and alignment. The PAL-PD uses the junction side for signal readout and the ohmic side for the X-ray entrance. It has guard-ring and field-shaper structures and is designed into four types to compare the performances depending on the metal structures of each side. We measured the electrical characteristics, leakage current and bulk capacitance of the PAL-PD as a function of reverse bias voltage. The operating bias voltage was determined to be -200 V from the bulk capacitance measurement. The leakage current and capacitance were measured to be about 20 nA/cm2 and 20 pF at the operating voltage, respectively. The quantum efficiency as a function of wavelength was measured to be about 100% at 550 nm wavelength. The signal-to-noise ratio was measured using Sr-90 radioactive source and energy resolution was measured using Am-241 and Ba-133 gamma radioactive sources. The beam test was performed using a soft X-rays of 600, 900, and 1200 eV at Pohang Accelerator Laboratory X-ray Free Electron Laser. The performance of the PAL-PD was compared with that of a commercial PD used at the PAL-XFEL. In this paper, we present measurements and experiment results of the PAL-PD.

AcknowledgmentThis research was supported by National Research Foundation of Korea grants 2018R1D1A1B07047294 and 2019K1A3A7A09034974, the Radiation Science Research Institute (RSRI). The EDA tool was supported by the IC Design Education Center (IDEC), Korea.
Keywords: PIN Photodiode, Quantum efficiency, Energy resolution, Soft X-ray, PAL-XFEL

Our exhibitors and sponsors – click on name to visit booth: