Photomultiplier for High Radiation and Magnetic Fields
Conversion of the Weapon Technology in Photoelectronic Technique for the Construction of a Photo-detector Generation for the Performance in Super-high Magnetic and Radiation Environment in Experimental High Energy Physics
Tech Area / Field
- INS-DET/Detection Devices/Instrumentation
3 Approved without Funding
Central Research Institute "Electron", Russia, St Petersburg
- Nuclear Physics Institute, Russia, Leningrad reg., Gatchina\nRussian Academy of Sciences / Institute of Nuclear Research, Russia, Moscow
- Université de Claude Bernard-Lyon 1 / Institut de Physique Nucléaire de Lyon, France, Lyon\nUniversity of Bristol, UK, Bristol
In this project it is proposed to use a scientific and technical potential, achievements and unique experience accumulated in NRI “Electron” last 50 years in the field of photo-television devices intended for detection and guidance systems of weapons in order to create a new class of photomultipliers (PMT) of broad civil and scientific application.
The prime purpose of the project is a creation of the mass production technology of PMT-triode with the immunity to magnetic field up to 4 Tesla being the elementary representative of the future class of Fine-Mesh PMT (FMPMT). Creation of this technology will allow to solve a problem of delivery unusually large batches of magnetically – and radiation-hard photodetectors necessary for nuclear – physical experiments at the floor price.
At present the progress in the study of fundamental matter properties revealing in the interaction of particles and nuclei at super high energies is concerned with proposed experiments on building in CERN (Switzerland) Large Hadron Collider-LHC. Physical investigations will be carried out on four Detectors: ATLAS, CMS, ALICE and LHC-B. One of the main tasks of experiments planning to be done at LHC is the search of the Standard Model Higgs Bason over a mass range 80 GeV – 1TeV selected by their decays into two and four gamma-quants of high energy. Out of the four Detectors under construction, only CMS Compact Muon Solenoid is proposed to use as a high energy Gamma and Electrons detector – Electromagnetic Calorimeter (ECAL) possessing the highest energy resolution. The biggest detectors ATLAS and CMS are proposed to perform in extremely intensive beams of particles, at the radiation doses up to a few MRad per year and detection efficiency of about 100%. High requirements to energy and angular resolution of ECAL CMS are defined by its high granularity – more than 100,000 pixels. It is necessary to note that CMS ECAL should perform in super high magnetic field (4 Tesla) and should provide the light collection during 25-30 nsec. For this goal as scintillators the lead tungstate crystals (PWO) were chosen, which mass production process development in Bogoroditck is already financed by ISTC.
At the present moment is decided, that for detectors, located in EndCaps of the calorimeter, i.e. in a zone of the greatest radiation effect, the avalanche photodiodes (APD) due to their disadvantage – high radiation sensitivity and the nuclear counter effect can not be used. So the application of photo multipliers which are capable to function continuously within several years in the strong magnetic field (4 T), with absorbed dose up to 10 Mrad/year and having the Energy resolution compared with APD is required. The second requirement means that a crystal as photodetector In total, produced samples of PWO correspond to such time conditions. Photodetectors proposed to use in barrel part of ECAL are silicon avalanche photodiodes which have inner amplification of 50 – 60 and insensitive to the magnetic field. But APD characterized rather low radiation hardness and can be used in of ECAL where radiation doses per year are of order of 10 MRad. Alternative option of photodetectors performing in strong magnetic fields (4 Tesla), radiation hard to the dose of 10 MRad per year and having the energy resolution comparable with APD would be Fine-Mesh Phototetrodes and Phototriodes. Such detectors with the gain of 8 – 10 in magnetic field of 4 Tesla and the photocathode's area of 2.5 cm2 will have the efficiency of the light detection from PWO scintillators close to that of APD, but without the disadvantage of APD – the nuclear counter effect.
The prototypes devices (triodes, tetrodes, 15-stage) under the initiative of Russian Institutes – PNPI and MEPI were created by NRI "Electron" in the shortest terms. The devices successfully have passed tests in leading nuclear – physical centres (CERN(Switzerland), BNL (USA)). Based on results of testing of Phototriodes, the decision of maintenance of half need (8000 pieces for experiment CMS) by Russian devices is accepted. The similar devices will be developed and delivered by the “Electron Tubes Ltd” (Ruislip, UK).
During researches and technology optimization Russian and western participants institutions will performe: tests in magnetic, radiation fields, and tests on a high energy particles beams at accelerators (PNPI, INR RAS, Russia), simulation of the characteristics of pmts optimising design (University Bristol, UK), development of radiation-hard low-noise electronics with broad dynamic range (Institute of nuclear Physics, Lyons, France).
Long-range goal of the project is to create a new family of devices (from a triode with gain of 10 times up to 16 cascades with gain up to 106) of wide civil and scientific application. Here the positive experience is present too, – the laboratory technology and PMTdesign with 15-stage fine mesh is developed. These PMTs are suitable for activity in magnetic fields up to 1Tesla and are planned to use for Time-Of-Flight (TOF) system of experiment STAR on Heavy – Ion Collider (RHIC) in Brokhaven National Laboratory of USA. The test of experimental samples showed their identity for the experiments requires. There are all premises, that it is possible to create on its base devices which are capable hereafter to replace classical PMT in many applications. By research and perfecting both of a Phototriode and 15-stage technology the base design and technology will be created. The optimization of engineering decisions, obtained from triodes improvement, on a large batches will allow for a series of multistage devices to achieve a combination of high parameters with devices price cut of too. Main distinctive features of such devices from classical PMT will be the use of special finemesh dynodes for multiplication cascades assembled in proximity design, that provides small overall dimensions, improved time characteristics, high immunity to magnetic fields.
Accumulated experience in manufacture of devices for military goals in NRI Electron, usage of available technology and its upgrade for the construction of photodetectors for scientific application, the presence of qualified engineers and workers indisputably would encourage to solve the tasks of this Project. Such conversion process will appear also useful to an effective utilization of the scientists, and experts increasing of their employment. The realization of this project in ISTC frameworks will allow to submit to the scientists and experts occupied earlier in RNI "ELECTRON" on defensive subjects, to use available scientific and technical potential at a realization of international technical problems, will ensure with their working places. Financing from ISTC necessary to realize this Project is especially important for Russian side which is responsible together with the UK for the construction of ENDCAP ECAL CMS. Institute of High Energy Physics (IHEP, Protvino), Petersburg Nuclear Physics Institute (PNPI), Institute of Nuclear Research (INR, Troitsk) and others will participate in the realization of ENDCAP ECAL Program.
The Project will not only draw a few electronic factories of Russia from weapons directions to the production of scientific devices for the next 5 – 10 years, but will also allow physicists and engineers of Russian Institutes to take a larger part in the construction of ECAL CMS system. Participating in the Project and collaborating with foreign institutes involved in CMS experiment, scientists and engineers of Russian military industry will be able to develop new technologies for the manufacture of different non-military production. Successful collaboration in the framework of the Project can lead in future to new contracts between Western Institutes and Russian industry.
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