The COMPASS measurements of the azimuthal asymmetries in the hadron pairs production in DIS on transversely polarised targets are here presented. Results on oppositely charged pion and kaon pairs ...produced on both deuteron and proton targets are shown. They have been used to update the calculation of the Transversity function which was previously extracted from the asymmetries measured from un-identified hadron pairs. Also a new method for the direct measurement of the integral of Transversity using both COMPASS and BELLE results is presented.
In recent years information on the transversity distribution h1 has been obtained by combining the Collins asymmetry results from semi-inclusive deep inelastic scattering (SIDIS) data on transversely ...polarized nucleon targets with the information on the fragmentation function of a transversely polarized quark from the asymmetries measured in e+e− annihilation into hadrons. An alternative method was proposed a long time ago, which does not require the e+e− data but allows one to get ratios of the u and d quark transversity distributions from the SIDIS data alone. The method utilizes the ratio of the difference of the Collins asymmetries of positively and negatively charged hadrons produced on transversely polarized proton and deuteron targets. We have applied this method to the COMPASS proton and deuteron data and extracted the ratio h1dv/h1uv. The results are compared to those obtained in a previous point-by-point extraction based both on SIDIS and e+e− data.
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 1.5m2 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 single photon detectors. All aspects of the upgrade are presented, including engineering, mass production, quality assessment and performance.
Perspectives for further developments in the field of gaseous single photon detectors are also presented.
The study of the spin structure of the nucleon and of the effects rising from the quarks transverse momentum are part of the scientific program of COMPASS, a fixed target experiment at the CERN SPS. ...The azimuthal asymmetries which appear in the cross-section of SIDIS off unpolarized targets can give insights on the intrinsic momentum structure of the nucleon and on the possible correlation between transverse spin and transverse momentum of the quarks. Here we present the new results for these asymmetries obtained from the COMPASS data collected with a 160 GeV/c positive muon beam impinging on a 6LiD target. The asymmetries are measured for both positive and negative hadrons, and their dependence on several kinematical variable has been studied.
In 2016 we have upgraded the COMPASS RICH by novel gaseous photon detectors based on MPGD technology. Four new 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. The new detector architecture consists in a hybrid MPGD combination: two layers of THGEMs, the first of which also acts as a reflective photocathode thanks to CsI coating, are coupled to a bulk Micromegas on a pad-segmented anode. These detectors are the first application in an experiment of MPGD-based single photon detectors. Presently, we are further developing the MPGD-based PDs to make them adequate for a setup at the future EIC collider. All aspects of the COMPASS RICH-1 Photon Detectors upgrade are presented: R&D, engineering, mass production, QA and performance; the on-going development for collider application is also presented.
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 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 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.
THGEM based photon detector for Cherenkov imaging applications Alexeev, M.; Birsa, R.; Bradamante, F. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
05/2010, Letnik:
617, Številka:
1
Journal Article
Recenzirano
We are developing a single photon detector for Cherenkov imaging counters. This detector is based on the use of THGEM electron multipliers in a multilayer design. The major goals of our project are ...ion feedback suppression down to a few per cent, large gain, fast response, insensitivity to magnetic fields, and a large detector size.
We report about the project status and perspectives. In particular, we present a systematic study of the THGEM response as a function of geometrical parameters, production techniques and the gas mixture composition. The first figures obtained from measuring the response of a CsI coated THGEM to single photons are presented.
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