Status and characterisation of COMPASS RICH-1 Albrecht, E.; Baum, G.; Birsa, R. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
11/2005, Letnik:
553, Številka:
1
Journal Article
Recenzirano
COMPASS RICH-1, a gas-radiator RICH detector with large transversal dimensions, which makes use of MWPC with CsI photocathodes as photon detectors, is in operation at COMPASS since 2001. The ...behaviour of the detector components is optimised and fully understood. The characterisation of the detector is now complete. We report about the detector status and its response in the COMPASS environment.
Conventional radiation chemistry of polymers is based on studies of irradiation with electron beams or gamma-rays, both of which are low ionization density (low LET) radiations. In such systems the ...radiation energy is deposited homogeneously and absorbed dose is expressed in terms of ‘Grays’ (Joules per kg). Heavy ion beams represent high ionization density (high LET) radiations that deposit their energy inside separate tracks, in the bulk of which the polymeric material is severely disintegrated into low molecular weight products. An ‘average dose’ can be defined in such systems, but the effective ‘local dose’ inside the tracks can only be estimated very roughly with a more or less arbitrary assumption of the effective volume of the track. In polymers subjected to low LET radiation the following chemical modifications are observed: gas evolution, formation of unsaturation, main-chain cleavage and/or cross-linking, depending on the chemical nature of the polymer. Oxygen, if present during irradiation, induces oxidative degradation processes, which may lead to significant main-chain scission, even in polymers of the cross-linking type. High LET radiations produce very severe damage to the polymeric material inside the tracks. The latter may be visualized by dissolving out the degraded material with aqueous solutions that do not affect the original polymer. This major chemical trasformation results from multiple bond scissons in single molecules, directly caused by the high density of energy deposition. Chemical effects of similar nature are produced under the action of glow discharges and of laser breams but the resulting products are not the same as those produced by ion beams in view of the large differences in irradiation conditions.
Radiations are used efficiently and economically for the production of new or modified polymers. The following processes are considered:
1.
Radiation curing;
2.
Radiation cross-linking;
3.
Radiation ...grafting.
These processes are commonly used today in industry and provide a broad range of new potential applications in various fields. The history of their development is briefly reported. The chemical reactions underlying these processes are described.
(1) Radiation curing is used commercially on a large scale for the production of improved coatings, lacquers and inks. The process can be conducted at very high speeds. Curing of magnetic formulations leads to particularly stable products, which compete favourably with more conventional materials.
(2) Radiation cross-linking is an established technology in the wire and cable industry. It emparts to the modified insulators improved resistance to solvents, to ageing and to elevated temperatures. The resulting cross-linked network also reduces the migration of fillers and thereby stabilizes in time any message imprinted with magnetic or colored pigments dispersed in a polymer.
(3) Radiation grafting is a powerful method for modifying more profoundly the properties of a polymer and for creating numerous, entirely new materials. The chemical modification can be applied at will into the bulk of the material or limited to a surface zone of any desired depth. This method can be used for instance, for introducing polar groups in the bulk or on the surface of non-polar polymers, for increasing or reducing the wettability of a polymer, for imparting a better compatibility of a polymer to a specific coating and the like.
The irradiation of water-soluble polymers in aqueous solutions, with or without the addition of another monomer gives rise to a variety of cross-linked gels which find useful applications in the biomedical field. Other promising applications will be considered.
COMPASS RICH-1 Albrecht, E.; Baum, G.; Birsa, R. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
04/2003, Letnik:
502, Številka:
1
Journal Article
Recenzirano
RICH-1 is a large acceptance gaseous RICH using 3m of C4F10 as radiator and MWPCs with CsI photo-cathodes as VUV photon detectors. The main characteristics of this RICH are the large acceptance and ...the use of far UV photon detectors, which implies large dimensions, UV transparencies of the elements up to the photo-cathode, and good UV mirror reflectance.
We give a description of the detector, first results about its performances and a report about various technological achievements required by this challenging project.
The radiator gas and the gas system of COMPASS RICH-1 Albrecht, E.; Baum, G.; Bellunato, T. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
04/2003, Letnik:
502, Številka:
1
Journal Article
Recenzirano
Odprti dostop
The design of the COMPASS RICH-1 gas system, its operational modes, the cleaning setups for the preparation of the radiator gas and transmission measurement installations are described. The gas ...system in presently fully operational and satisfactory transmission of VUV light through the radiator gas has been reached.
The mirror system of COMPASS RICH-1 Albrecht, E.; Baum, G.; Birsa, R. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
04/2003, Letnik:
502, Številka:
1
Journal Article
Recenzirano
Odprti dostop
The architecture and the properties of the mirror system of the COMPASS RICH-1 detector, composed by 116 spherical VUV reflecting units supported by a lightweight mechanical structure, are described.
First performances of COMPASS RICH-1 Albrecht, E.; Baum, G.; Bellunato, T. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
02/2004, Letnik:
518, Številka:
1
Journal Article
Recenzirano
Odprti dostop
COMPASS RICH-1, designed in 1996 for hadron identification at high momenta in the COMPASS large angle spectrometer, is based on the use of MWPCs with large size CsI photon detectors. This choice, ...dictated by technical and economical considerations, has imposed VUV requirements for mirror reflectance and radiator transparency.
The detector is now fully operative and its preliminary performances are presented.
The COMPASS RICH-1 read-out system Baum, G.; Birsa, R.; Bradamante, F. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
04/2003, Letnik:
502, Številka:
1
Journal Article
Recenzirano
Odprti dostop
This paper describes the reconfigurable read-out system for the 82944 RICH-1 channels of the COMPASS experiment (NA58) at CERN. The system is based on 192 identical large front-end boards (BORA ...board). BORA was designed for acquiring, digitizing, threshold subtracting and transmitting event data. The overall operation of the board is controlled and supervised by a DSP tightly interacting with an FPGA that acts as a parallel co-processor. The DSP allows characterizing each analog channel by locally calculating noise and pedestal. Each BORA communicates with the outside world through two optical fibers and through a dedicated DSP network. One optical fiber is used to receive event triggers, and the other one is used to transmit event data to subsequent processing stages of the acquisition system. The DSP network allows reconfiguring and reprogramming the DSPs and FPGAs as well as acquiring sample events to visualize the overall operation of the system. The whole RICH has eight DSP networks working in parallel. These networks are handled by DOLINA, a PC resident multiprocessor board containing eight DSPs. Each network is formed by 24 BORA DSPs and 1 DOLINA DSP. The read-out system can steadily work up to a trigger rate of 75kHz with maximum pixel occupancy of 20%, reaching a transmission data rate of 5.13Gbytes/s.
