There are several applications and fundamental research areas which require the detection of VUV light at cryogenic temperatures. For these applications we have developed and successfully tested special designs of gaseous detectors with solid photocathodes able to operate at low temperatures: sealed gaseous detectors with MgF2 windows and windowless detectors. We have experimentally demonstrated, that both primary and secondary (due to the avalanche multiplication inside liquids) scintillation lights could be recorded by photosensitive gaseous detectors. The results of this work may allow one to significantly improve the operation of some noble liquid gas TPCs.
The operation of visible-sensitive gaseous- and, to some extent, vacuum-photomultipliers is critically affected by secondary electrons originating from ion impact on the photocathode. A simple method for indirect measurement of the effective ion-induced secondary-electron emission (IISEE) coefficient from the photocathode into a gas medium, $γ_+^{eff}$ was developed. The experimental results with visible-sensitive K-Cs-Sb, Na-K-Sb and Cs-Sb photocathodes, yielded $γ_+^{eff}$ - values between 0.02 and 0.03 in Ar/CH$_{4}$ (95/5) at 700 mbar; these are in good agreement with theoretical calculati…
Noble gases and liquids are excellent scintillators and this opens a unique opportunity to directly detect the primary scintillation light produced in these media by photons or particles. This signal can be used for several purposes, for example as a start signal for TPCs or for particles identification. Usually photomultipliers (PMs) are used for the detection of the scintillation light. In our previous work we have demonstrated that costly PMs could be replaced by gaseous detectors with CsI photocathodes . Such detectors have the same quantum efficiency as the best PMs but at the same time a…
We summarize the development of visible-sensitive gaseous photomultipliers, combining a semitransparent bi-alkali photocathode with a state-of-the-art cascaded electron multiplier. The latter has high photoelectron collection efficiency and a record ion blocking capability. We describe in details the system and methods of photocathode production and characterization, their coupling with the electron multiplier and the gaseous-photomultiplier operation and characterization in a continuous mode. We present results on the properties of laboratory-produced K$_2$CsSb, Cs$_3$Sb and Na$_2$KSb photoca…
We review latest progress in gaseous photomultipliers (GPM) combining solid photocathodes and various types of novel electron multipliers. Cascaded gaseous electron multipliers (GEM) coated with CsI photocathodes can efficiently replace UVsensitive wire chambers for single-photon recording in Cherenkov and other detectors. Other hole-multipliers with patterned electrodes (Micro-Hole and Strip Plates) and improved ion-blocking properties are discussed; these permit reducing considerably photon- and ion-induced secondary effects. Photon detectors with other electron-multiplier techniques are bri…
Currently a revolution is happening in the development of gaseous detectors of photons and particles. Recently developed gaseous detectors with solid photocathodes are now replacing photosensitive wire chambers, which dominated for years in high energy and space flight experiments. We will review the main developments in this field as well as their applications in high-energy physics, medicine, industry and plasma diagnostics. New results on solid photocathodes coupled with gaseous micropattern/wire detectors will also be presented.
We report on the progress in the study of cascaded GEM and GEM/MHSP gas avalanche photomultipliers operating at atmospheric pressure, with CsI and bialkali photocathodes. They have single-photon sensitivity, ns time resolution and good localization properties. We summarize operational aspects and results, with the highlight of a high-gain stable gated operation of a visible-light device. Of particular importance are the results of a recent ion-backflow reduction study in different cascaded multipliers, affecting the detector's stability and the photocathode's liftime. We report on the signific…
This paper describes the present status of the aging studies in various photosensitive detectors. New experimental data are presented on aging of trimethilamine (TMA) and ethilferrocene (EF) photosensitive vapors as well as on CsI and SbCs photocathodes. A new explanation of the CsI photocathodes aging process based on solid state physics theory is given. Finally, based on our studies, a general conclusion was made that thin polymer depositions on the detector=92s cathode due to the aging can provoke breakdowns through the Malter-type mechanism (or more precisely- an explosive field emission m…
We are developing gaseous photon detectors for Cherenkov imaging applications in the experiments at the future Electron Ion Collider. CsI, converting photons in the far ultraviolet range, is, so far, the only photoconverter compatible with the operation of gaseous detectors. It is very delicate to handle due to its hygroscopic nature: the absorbed water vapour decomposes the CsI molecule. In addition, its quantum efficiency degrades under ion bombardment. These are the key reasons to quest for novel, less delicate materials for photocathodes adequate for gaseous photon detectors. Layers of hyd…
A novel concept for ion blocking in gas-avalanche detectors was developed, comprising cascaded micro-hole electron multipliers with patterned electrodes for ion defocusing. This leads to ion blocking at the 10^{-4} level, in DC mode, in operation conditions adequate for TPCs and for gaseous photomultipliers. The concept was validated in a cascaded visible-sensitive gas avalanche photomultiplier operating at atmospheric pressure of Ar/CH_{4} (95/5) with a bi-alkali photocathode. While in previous works high gain, in excess of 10^{5}, was reached only in a pulse-gated cascaded-GEM gaseous photom…
We shortly describe recent progress in photon detectors combining bi-alkali photocathodes and cascaded patterned gas-avalanche electron multipliers. It permitted the development and the first feasibility demonstration of high-gain gaseous photomultipliers sensitive in the visible spectral range, operated in DC mode with single-photon sensitivity.
We have developed commercial prototypes of sealed gaseous detectors combined with CsI photocathodes and/or filled with photosensitive vapors. The rirst results of application of these devices for the detection of flames in daylight conditions and for the detection of scintillation lights from noble liquids will be presented. The main conclusion from our studies is that for some applications the sealed UV sensitive gaseous detectors have superior performance (higher practical quantum efficiency and better signal to noise ratio) than existing commercial UV sensitive detectors. Additionally, they…
We have developed a cost effective technology for manufacturing various layouts of micropattern gaseous detectors for a wide range of applications. Such devices feature resistive electrodes interfaced to a network of thin readout strips/electrodes. The following three examples of such innovative designs and their applications will be presented: a prototype of a novel double-phase LAr detector with a CsI photocathode immersed inside the LAr, a CsI-RICH detector prototype for ALICE upgrade and GEM-like sensors for environmental safety/security applications.
We have demonstrated that hole-type gaseous detectors, GEMs and capillary plates, can operate up to 77 K. For example, a single capillary plate can operate at gains of above 10E3 in the entire temperature interval between 300 until 77 K. The same capillary plate combined with CsI photocathodes could operate perfectly well at gains (depending on gas mixtures) of 100-1000. Obtained results may open new fields of applications for capillary plates as detectors of UV light and charge particles at cryogenic temperatures: noble liquid TPCs, WIMP detectors or LXe scintillating calorimeters and cryogen…
In the context of the development of novel Thick GEM based detectors of single photons, the high resolution optical system, nicknamed Leopard, providing a detailed surface scanning of the Thick GEM electron multipliers, has been used for a set of systematic measurements of key Thick GEM properties. These results are reported and discussed. They confirm by direct observation Thick GEM properties previously inferred by indirect measurements and answer to relevant questions related to the use of Thick GEMs as photocathode substrates in novel gaseous photon detectors.
Gaseous PhotoMultipliers (GPM) are a very promising alternative of vacuum PMTs especially for large-size noble-liquid detectors in the field of Functional Nuclear Medical Imaging and Direct Dark Matter Detection. We present recent characterization results of a Hybrid-GPM made of three Micropattern Gaseous Structures; a Thick Gaseous Electron Multiplier (THGEM), a Parallel Ionization Multiplier (PIM) and a MICROMesh GAseous Structure (MICROMEGAS),operating in Ne/CF4 (90:10). Gain values close to 10^7 were recorded in this mixture, with 5.9keV x-rays at 1100 mbar, both at room temperature and at…
Presented here are first tests of a Gaseous Photomultiplier based on a cascade of Thick GEM structures intended for gamma-ray position reconstruction in liquid Argon. The detector has a MgF$_2$ window, transparent to VUV light, and a CsI photocathode deposited on the first THGEM. A gain of $8\cdot10^{5}$ per photoelectron and $\sim100\%$ photoelectron collection efficiency are measured at stable operation settings. The excellent position resolution capabilities of the detector (better than 100 $μ$m) at 100 kHz readout rate, is demonstrated at room temperature. Structural integrity tests of the…
We have developed and successfully used several innovative designs of detectors with solid photocathodes. The main advantage of these detectors is that rather high gains (>10E4) can be achieved in a single multiplication step. This is possible by, for instance, exploiting the secondary electron multiplication and limiting the energy of the steamers by distributed resistivity. The single step approach also allows a very good position resolution to be achieved in some devices: 50 micron on line without applying any treatment method (like center of gravity). The main focus of our report is new fi…
We have studied gain vs. voltage characteristics and position resolutions of multistep capillary plates (two or three capillary plates operating in a cascade), as well as capillary plates operating in a mode when the main amplification occurs between plates or between the capillary plate and the readout plate (parallel plate amplification mode). Results of these studies demonstrated that in the parallel-plate amplification mode one can reach both high gains (>100000) and good position resolutions (~100 micro meter) even with a single step arrangement. It offers a compact amplification structur…
There are several proposals and projects today for building LXe Time Projection Chambers (TPCs) for dark matter search. An important element of these TPCs are the photomultipliers operating either inside LXe or in vapors above the liquid. We have recently demonstrated that photosensitive gaseous detectors (wire type and hole-type) can operate perfectly well until temperatures of LN2. In this paper results of systematic studies of operation of the photosensitive version of these detectors (combined with reflective or semi-transparent CsI photocathodes) in the temperature interval of 300-150 K a…
Operation results are presented of a UV-sensitive gaseous photomultiplier (GPM) coupled through a MgF2 window to a liquid-xenon scintillator. It consisted of a reflective CsI photocathode deposited on top of a THick Gaseous Electron Multiplier (THGEM); further multiplication stages were either a second THGEM or a Parallel Ionization Multiplier (PIM) followed by a MICROMEsh GAseous Structure (MICROMEGAS). The GPM operated in gas-flow mode with non-condensable gas mixtures. Gains of 10^4 were measured with a CsI-coated double-THGEM detector in Ne/CH4 (95:5), Ne/CF4 (95:5) and Ne/CH4/CF4 (90:5:5)…
The detection of primary scintillation light in combination with the charge or secondary scintillation signals is an efficient technique to determine the events t=0 as well as particle / photon separation in large mass TPC detectors filled with noble gases and/or condensed noble gases. The aim of this work is to demonstrate that costly photo-multipliers could be replaced by cheap novel photosensitive gaseous detectors: wire counters, GEMs or glass capillary tubes coupled with CsI photocathodes. We have performed systematic measurements with Ar, Kr and Xe gas at pressures in the range of 1-50 a…
Advances in photocathode development for PICOSEC Micromegas precise-timing detectors
European Organization for Nuclear Research (CERN)（欧洲核子研究组织）；University of Turin（都灵大学）；Middle East Technical University（中东技术大学）；Technion - Israel Institute of Technology（以色列理工学院）；IRFU, CEA, Université Paris-Saclay（巴黎萨克雷大学CEA IRFU）；Ludwig Maximilian University of Munich（慕尼黑路德维希-马克西米利安大学）；Weizmann Institute of Science（魏茨曼科学研究所）；Università di Pavia（帕维亚大学）；INFN Sezione di Pavia（意大利国家核物理研究院帕维亚分部）；Stony Brook University（石溪大学）
We discuss recent advances in the development of cryogenic gaseous photomultipliers (GPM), for possible use in dark matter and other rare-event searches using noble-liquid targets. We present results from a 10 cm diameter GPM coupled to a dual-phase liquid xenon (LXe) TPC, demonstrating - for the first time - the feasibility of recording both primary ("S1") and secondary ("S2") scintillation signals. The detector comprised a triple Thick Gas Electron Multiplier (THGEM) structure with cesium iodide photocathode on the first element; it was shown to operate stably at 180 K with gains above 10^5,…
Gamma-ray and fast-neutron imaging was performed with a novel liquid xenon (LXe) scintillation detector read out by a Gaseous Photomultiplier (GPM). The 100 mm diameter detector prototype comprised a capillary-filled LXe converter/scintillator, coupled to a triple-THGEM imaging-GPM, with its first electrode coated by a CsI UV-photocathode, operated in Ne/5%CH4 cryogenic temperatures. Radiation localization in 2D was derived from scintillation-induced photoelectron avalanches, measured on the GPM's segmented anode. The localization properties of Co-60 gamma-rays and a mixed fast-neutron/gamma-r…
Measurements of electron drift properties in liquid and gaseous xenon are reported. The electrons are generated by the photoelectric effect in a semi-transparent gold photocathode driven in transmission mode with a pulsed ultraviolet laser. The charges drift and diffuse in a small chamber at various electric fields and a fixed drift distance of 2.0 cm. At an electric field of 0.5 kV/cm, the measured drift velocities and corresponding temperature coefficients respectively are $1.97 \pm 0.04$ mm/$μ$s and $(-0.69\pm0.05)$\%/K for liquid xenon, and $1.42 \pm 0.03$ mm/$μ$s and $(+0.11\pm0.01)$\%/K …
Design and Performance of a 96-channel Resistive PICOSEC Micromegas Detector for ENUBET
Aristotle University of Thessaloniki（塞萨洛尼基亚里士多德大学）；Ludwig Maximilian University of Munich（慕尼黑路德维希-马克西米利安大学）；CERN（欧洲核子研究组织）；Stony Brook University（石溪大学）；NCSR Demokritos（德墨忒勒斯国家科学研究中心）；University of Bonn（波恩大学）；LIP（粒子物理与实验仪器实验室）；University of Helsinki（赫尔辛基大学）；Jefferson Lab（杰斐逊实验室）；University of Zagreb（萨格勒布大学）；University of Science and Technology of China（中国科学技术大学）；CEA-Saclay（法国原子能和替代能源委员会萨克雷中心）；National Technical University of Athens（雅典国立技术大学）；Ruđer Bošković Institute（鲁德·博什科维奇研究所）；University of Virginia（弗吉尼亚大学）
A simulation model is developed to train Artificial Neural Networks (ANN), for precise timing of PICOSEC Micromegas detector signals. The aim is to develop fast, online timing algorithms as well as minimising the information to be saved during data acquisition. PICOSEC waveforms were collected and digitised by a fast oscilloscope during a femptosecond-laser test beam run. A data set comprising waveforms collected with attenuated laser beam intensity, eradicating the emission of more than one photoelectron per light pulse from the PICOSEC photocathode, was utilised by a simulation algorithm to …
Timing performance of large prototype based on $\upmu$RWELL- PICOSEC detector technology with $10 \times 10\ \mathrm{cm}^{2}$ active area
European Organization for Nuclear Research (CERN)（欧洲核子研究中心）；Aristotle University of Thessaloniki（塞萨洛尼基亚里士多德大学）；Center for Interdisciplinary Research and Innovation (CIRI-AUTH)（跨学科研究与创新中心）；Institut de Recherche sur les lois Fondamentales de l’Univers (IRFU, CEA)（基础定律宇宙研究所）；Ludwig Maximilian University of Munich（慕尼黑路德维希-马克西米利安大学）
Two-dimensional solid state gaseous detector for thermal and cold neutrons is created. The detector has active area of 128 x 128 $mm^2$, $^{10}B$ neutron converter, and gas chamber with thin windows. The resistive charge-division readout is applied to determine the neutron position. The detector was tested using $W-Be$ photoneutron source at the Institute for Nuclear Research, Moscow. The detector efficiency is estimated as ~4% at neutron wavelength $λ= 1.82 Å$ and 8% at $λ= 8 Å$. The efficiency of the background detection was less than $10^{-5}$ of that for thermal neutrons. The resulting pul…
We have demonstrated experimentally that recently developed gaseous detectors combined with solid or gaseous photo-cathodes have exceptionally low noise and high quantum efficiency for UV photons while being solar blind. For this reason they can be used for the detection of weak UV sources in daylight conditions. These detectors are extremely robust, can operate in poor gas conditions and are cheap. We present the first results of their applications to hyper-spectroscopy and flame detection in daylight conditions.
A study of charge drift in a large scale optically transparent solid xenon is reported. A pulsed high power xenon light source is used to liberate electrons from a photocathode. The drift speeds of the electrons are measured using a 8.7\,cm long electrode in both the liquid and solid phase of xenon. In the liquid phase (163\,K), the drift speed is 0.193 $\pm$ 0.003 cm/$μ$s while the drift speed in the solid phase (157\,K) is 0.397 $\pm$ 0.006 cm/$μ$s at 900 V/cm over 8.0\,cm of uniform electric fields. Therefore, it is demonstrated that a factor two faster electron drift speed in solid phase x…
Nowadays neutron facilities are going toward higher fluxes, e.g. the European Spallation Source (ESS) in Lund (Sweden), and this translates into a higher demand in the instrument performances. Because of its favorable properties,He-3 has been the main actor in thermal neutron detection for years. Starting in about 2001 the He-3 stockpile has been declining. The world is now experiencing the shortage of He-3. This makes the construction of large area detectors (several squared meters) not realistic anymore. A way to reduce the He-3 demand for those applications is to move users to alternative t…
The PICOSEC detection concept consists in a "two-stage" Micromegas detector coupled to a Cherenkov radiator and equipped with a photocathode. A proof of concept has already been tested: a single-photoelectron response of 76 ps has been measured with a femtosecond UV laser at CEA/IRAMIS, while a time resolution of 24 ps with a mean yield of 10.4 photoelectrons has been measured for 150 GeV muons at the CERN SPS H4 secondary line. This work will present the main results of this prototype and the performance of the different detector configurations tested in 2016-18 beam campaigns: readouts (bulk…
A novel concept is proposed for large-volume single-phase noble-liquid TPC detectors for rare events. Both radiation-induced scintillation-light and ionization-charge are detected by Liquid Hole-Multipliers, LHM, immersed in the noble liquid. The latter may consist of cascaded Gas Electron Multipliers (GEM), Thick Gas Electron Multiplier (THGEM) electrodes or others, coated with CsI UV-photocathodes. Electrons, photo-induced on CsI by primary scintillation in the noble liquid, and event-correlated drifting ionization electrons are amplified in the cascaded elements primarily through electrolum…
There are several applications which require high position resolution UV imaging. For these applications we have developed and successfully tested a new version of a 2D UV single photon imaging detector based on a microgap RPC. The main features of such a detectors is the high position resolution - 30 micron in digital form and the high quantum efficiency (1-8% in the spectral interval of 220-140 nm). Additionally, they are spark- protected and can operate without any feedback problems at high gains, close to a streamer mode. In attempts to extend the sensitivity of RPCs to longer wavelengths …
In this study we report the results of a systematic study of the gain, rate and the position resolution limits of various micropattern gaseous detectors. It was found that at low rates (<1 Hz/mm^2) each detector has it own gain limit, which depends on the size and design features, as well as on gas composition and pressure. However, in all cases the maximum achievable gain is less than or equal to the classical Raether limit. It also was found that for all detectors tested the maximum achievable gain drops sharply with the counting rate. The position resolution of micropattern detectors for de…
After pioneering gaseous detectors of single photon for RICH applications using CsI solid state photocathodes in MWPCs within the RD26 collaboration and by the constructions for the RICH detector of the COMPASS experiment at CERN SPS, in 2016 we have upgraded COMPASS RICH by novel gaseous photon detectors based on MPGD technology. Four novel photon detectors, covering a total active area of 1.5~m$^2$, have been installed in order to cope with the challenging efficiency and stability requirements of the COMPASS physics programme. These detectors are the first application in an experiment of MPG…
After pioneering gaseous detectors of single photon for RICH applications using CsI solid state photocathodes in MWPCs within the RD26 collaboration and by the constructions for the RICH detector of the COMPASS experiment at CERN SPS, in 2016 we have upgraded COMPASS RICH by novel gaseous photon detectors based on MPGD technology. Four novel photon detectors, covering a total active area of 1.5~m$^2$, have been installed in order to cope with the challenging efficiency and stability requirements of the COMPASS physics programme. They are the first application in an experiment of MPGD-based sin…
Particle IDentification (PID) is a central requirement of the experiments at the future EIC. Hadron PID at high momenta by RICH techniques requires the use of low density gaseous radiators, where the challenge is the limited length of the radiator region available at a collider experiment. By selecting a photon wavelength range in the far UV domain, around 120 nm, the number of detectable photons can be increased. Ideal sensors are gaseous Photon Detectors (PD) with CsI photocathode, where the status of the art is represented by the MPGD-based PDs at COMPASS RICH. Detector optimization is requ…
Basic scaling laws are used to compare the relative capabilities of gaseous and solid-state tracking. Conclusions are drawn in the context of physics processes expected to be at the focus of studies at the International Linear Collider.
μRWELL-PICOSEC: Precision Timing with Resistive Micro-Well Detector
Thomas Jefferson National Accelerator Facility（托马斯·杰斐逊国家加速器设施）；IRFU, CEA, Université Paris-Saclay（IRFU, 法国原子能和替代能源委员会, 巴黎萨克雷大学）；Department of Physics, Aristotle University of Thessaloniki（塞萨洛尼基亚里士多德大学物理系）；Center for Interdisciplinary Research and Innovation (CIRI-AUTH)（跨学科研究与创新中心）；Department for Medical Physics, Ludwig Maximilian University of Munich（慕尼黑路德维希-马克西米利安大学医学物理系）；European Organization for Nuclear Research (CERN)（欧洲核子研究组织）；Dipartimento di Fisica, Università di Pavia（帕维亚大学物理系）；INFN Sezione di Pavia（意大利国家核物理研究所帕维亚分部）；Department of Physics and Astronomy, Stony Brook University（石溪大学物理与天文学系）；Institute of Nuclear and Particle Physics, NCSR Demokritos（国家科学研究中心德谟克利特研究所核与粒子物理研究所）
In the last few years our group have focused on developing various designs of spark-protected micropattern gaseous detectors featuring resistive electrodes instead of the traditional metallic ones: resistive microstrip counters, resistive GEM, resistive MICROMEGAS. These detectors combine in one design the best features of RPCs (spark-protection) and micropattern detectors (a high position resolution). In this paper we report the progress so far made in developing other types of resistive micropattern detectors: a microdot-microhole detector and a microgap-microstrip detector. The former detec…
Resistive gaseous detectors can be broadly defined as those operated in conditions where virtually no field lines exist that connect any two metallic electrodes sitting at different potential. This condition can be operationally recognized as 'no gas gap being delimited by two metallic electrodes'. Since early 70's, Resistive Plate Chambers (RPCs) are the most successful implementation of this idea, that leads to fully spark-protected gaseous detectors, with solid state-like reliability at working fields beyond 100kV/cm, yet enjoying the general characteristics of gaseous detectors in terms of…
Electroluminescence produced during avalanche development in gaseous avalanche detectors is an useful information for triggering, calorimetry and tracking in gaseous detectors. Noble gases present high electroluminescence yields, emitting mainly in the VUV region. The photons can provide signal readout if appropriate photosensors are used. Micropattern gaseous detectors are good candidates for signal amplification in high background and/or low rate experiments due to their high electroluminescence yields and radiopurity. In this work, the VUV light responses of the Gas Electron Multiplier and …
