We present an indirect measurement of possible long term variations of the CsI quantum efficiency in solid state photocathodes in MWPC. This type of photon detectors has been used since 2001 in the ...Cherenkov Imaging detector RICH-1 of the COMPASS experiment at CERN SPS. Data from six years of COMPASS data taking are used to evaluate the mean number of detected photons per particle. The results do not indicate any severe CsI quantum efficiency ageing effect.
We report about the development status of large area gaseous single photon detectors based on a novel hybrid concept for RICH applications.
The hybrid concept combines Thick Gaseous Electron ...Multipliers (THGEMs) coupled to CsI, working as a photon sensitive pre-amplification stage, and Micromegas, as a multiplication stage. The most recent achievements within the research and development programme consist in the assembly and study of 300×300mm2 hybrid photon detectors, the optimization of front-end electronics, and engineering towards large area detectors. Hybrid detectors with an active area of 300×300mm2 have been successfully operated in laboratory conditions and at a CERN PS T10 test beam, achieving effective gains in the order of 105 and good time resolution (σ=7ns); APV25 front-end chips have been coupled to the detector resulting in noise levels lower than 1000 electrons; the production and characterization of 300×600mm2 THGEMs is ongoing.
A set of hybrid detectors with 600×600mm2 active area is envisaged to upgrade COMPASS RICH-1 at CERN in 2016.
•The hybrid detector is a novel concept for large area gaseous photon detectors.•The hybrid concept combines Thick Gaseous Electron Multipliers and Micromegas.•The COMPASS RICH-1 upgrade will adopt hybrid detectors to replace the existing MWPCs
We are developing large size THick GEM (THGEM)-based detectors of single photons, mainly meant for Cherenkov imaging applications. The R&D programme includes the complete characterisation of the ...THGEM electron multipliers, the study of the aspects related to the detection of single photons and the engineering towards large size detector prototypes. Our most recent achievements include dedicated studies concerning the ion backflow to the photocathode; relevant progress in the engineering aspects, in particularly related to the production of large-size THGEMs, where the strict correlation between the local gain-value and the local thickness-value has been demonstrated and a 300300 mm super(2) active area detector has been successfully operated at the CERN PS T10 test beam; the introduction of a new hybrid detector architecture, offering promising performance, which is formed by a THGEM layer which acts both as photocathode and pre-amplification device, followed by a MICROMEGAS (MM) multiplication stage. We report about the general status of the R&D programme and, in detail, about the recent progress.
THGEM-based photon detectors for the upgrade of COMPASS RICH-1 Alexeev, M.; Birsa, R.; Bradamante, F. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
12/2013, Letnik:
732
Journal Article
Recenzirano
Odprti dostop
New Cherenkov photon detectors are being developed for the upgrade of COMPASS RICH-1. The detectors are based on THGEMs, arranged in a three layer architecture, with a CsI film on the first layer ...acting as a reflective photocathode. The response of THGEMs with various geometries under different conditions has been studied and photon detector prototypes have been built, tested in laboratory and operated during test beam runs providing a typical gain of 105 and a time resolution of better than 10ns. A photon detector prototype with 300×300mm2 active area, operated at the CERN PS T10 test beam in November 2012, has confirmed the validity of this novel technology and has allowed further studies of the detector response.
•The COMPASS THGEM R&D team has performed systematic studies and parameter optimization for THGEMs to be used in RICH applications.•A triple-THGEM photon detector with 300×300mm2 active area has been successfully tested at the CERN PS T10 test-beam.•A photon detector prototype based on coupling THGEM and Micromegas has provided encouraging results in laboratory tests.•For the upgrade of COMPASS RICH-1 a set of THGEM-based photon detectors will be produced.
Micropattern gaseous photon detectors for Cherenkov imaging counters Alexeev, M.; Birsa, R.; Bradamante, F. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
11/2010, Letnik:
623, Številka:
1
Journal Article
Recenzirano
We are developing a detector of single photons for application in Cherenkov imaging counters, based on the use of a multilayer architecture of THGEM electron multipliers coupled to a solid state CsI ...photocathode. The main goals of our project are ion feedback suppression down to a few per cent level, large gain, fast response, good time resolution, insensitivity to magnetic field and large detector size. We report about the project status and perspectives.
Progress towards a THGEM-based detector of single photons Alexeev, M.; Birsa, R.; Bradamante, F. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
05/2011, Letnik:
639, Številka:
1
Journal Article
Recenzirano
The novel and robust Thick GEM (THGEM) electron multiplier, coupled to a solid state photon converter, represents a promising option for instrumenting, at affordable costs, large areas with photon ...detectors, in particular, in Cherenkov imaging counters where single photons must be detected with high efficiency. The main goal of our project is to demonstrate the feasibility of reliable gaseous detector of single photons based on the use of THGEM multipliers, able to stably operate at high gain and high rate and to build and validate a large size prototype of such a detector. The project status and perspectives are reported; in particular attention is dedicated to the simulation and laboratory studies performed to understand the photo-electron extraction performance attainable using a solid state coated photo-cathode film onto a THGEM substrate.
Mirror alignment control for COMPASS RICH-1 detector Alexeev, M.; Birsa, R.; Bradamante, F. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
05/2011, Letnik:
639, Številka:
1
Journal Article
Recenzirano
The focusing system of the COMPASS RICH-1 detector consists of two segmented spherical mirror surfaces, formed by 68 hexagonal and 48 pentagonal individual elements. All individual mirrors have two ...degrees of freedom to adjust the angular alignment in order to obtain a continuous spherical surface. Relative angular misalignments can be monitored on-line by the CLAM method, based on the optical reconstruction of line images. Complementing the CLAM measurements with photogrammetry, the absolute mirror orientation and position in space can be determined too. The method is described, as well as the algorithms used to access the relative and absolute mirror alignment.
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