Photoelectronic Devices for High-Energy Physics and Medical Tomography
Tech Area / Field
8 Project completed
Senior Project Manager
Coevering G van de
NIIIT (Pulse Techniques), Russia, Moscow
- ITEF (ITEP), Russia, Moscow\nVNIIIMT (Medical Engineering), Russia, Moscow\nResearch Center "Geosphera", Russia, Moscow
- CTI PET Systems Inc., USA, TN, Knoxville\nUniversità di Roma "La Sapienza" / Instituto Nazionale di Fisica Nucleare, Italy, Rome\nUniversity of Massachusetts, Medical Center, USA, MA, Worcester\nCERN, Switzerland, Geneva
Project summaryThe present Project is aimed at development of photoelectronic devices for nuclear physics investigation, particularly for high energy physics: optoelectronic delay lines (OEDLs), magnetic image intensifiers (MIIs), photoelectronic multipliers (PMTs) for intense magnetic field environment and a PMT for a mobile photon emission computer tomograph (SPECT)
The OEDL can be used in reading systems of detectors on scintillation fibres (SCIFI) for experiments in high energy physics. These detectors will be used in beams of very high intensity within the range 107— 108 events per second. Only small part of these events is interesting to physicists and should be transferred to appropriate optoelectronic devices and reading system. The interesting events are chosen with the help of a trigger signal which initiated by various types of detectors, for example, scintillation counters or hodoscopes. This trigger signal can arrive with a delay of about 1 mcs. Therefore, the light signals from detectors should be delayed for this interval of time with the help of an OEDL.
At the second stage of the project the work on creation of OEDL with a diameter of the photocathode of 40 mm, the work on which was begun at the first stage, will bo continued, since at the first stage of the Project the basic questions of theoretical computations, design and production technology were not settled, but this is very urgent for manufacturing the devices like these in separate lots.
The developed OEDL prototype will be taken at the first stage as a basis of development of OEDL with a diameter of the photocathode of 200 mm.
Special electron —optical converters, namely light image intensifiers, capable to intensify the image sent on their cathode in intensive magnetic fields are necessary for amplification of the image of tracks of particles on the OEDL screen to a level necessary for transfer to a CCD — array. If necessary, on the OEDL output 2 or 3 similar light intensifiers can be successively mounted.
The image intensificr functioning in intensive magnetic fields (= 1 T) is the third photoelectronic device, design and technology of manufacturing of which are expected to be developed in the scope of the Project.
In recent time magnetostable PMTs are widely used in high energy physics research. For the experiments ATLAC and L.HCB in CERN magnetostable PMTs are required, particularly with a radiation stable input window and reduced to 40 mm length. The application magnetostable PMTs is planned also in the CERN «Felix» and «Caleido» Projects.
It was the aim of the Project to develop the magnetostable PMTs operable in magnetic environment of up to 3 Т without significant gain drop.
The recently developed method of single — photon emission computer tomography provides alongside with uninvasiveness brain perfusion detection as well. In particular, this method is used at transplantation of human organs.
Application of this method in cases of patients in coma demonstrated high specificity and reliability of brain death detection even in planar images. So the problem of brain death detection could be solved if physicians had at their disposal a tomograph which could be brought to the patient's bedside.
Scull injuries are leading causes of mortality in case of car accidents as well, so early detection of brain blood flow deterioration facilitates injury degree diagnosis and, as a consequence, transportation of the injured to a proper medical institution.
It is evident that there is an urgent need in a mobile single — photon tomograph, which could be transported inside a hospital or around a town in an ambulance vehicle.
All the above said gives grounds to assert that for realization of a mobile emission tomograph it is necessary to develop a square PMT with a square photocathode, specifications for which are stated below. The main Project goals
The main Project goals are follows:
1. Updating the design and technology of OEDL with 40 mm diameter of the photocathode, development OEDL with 200 mm diameter of the photocathode.
2. Design and development of production process of the image intensifier, of single and multistage magnetostable PMTs.
3. Study of these devices on installation of the Institute of High Energy Physics (Protvino, Russia) and on those of CERN (Geneva, Switzerland).
4. Design and development of production process the «flat» PMT with a square 10x60 photocathode. Development and manufacture of equipment for manufacture of parts and components of PMT, of measuring equipment and PMT models.
5. Research of parameters of PMT models for SPECT together with academician K. D. Kalantarov (Moscow , VNIIMP).
After completing the second stage of the project it is supposed to obtain for all six types of devices the following:
1. Complete set of the design —technological documentation for each type of devices.
2. Complete set of equipment for manufacturing all types of devices.
3. Prototype samples of each type of devices with parameters satisfying the technical requirements.
4. Protocols of research tests for all types of the devices executed together with the interested persons and agreed with foreign collaborators.
The development of six new types of photoelectronic devices is:
1. of scientific interest, which consists in opportunity of carrying out of scientific researches with the purpose of increasing the scientific potential in researched areas.
2. of commercial interest since the developed devices can be sold to interested firms. For instance, by preliminary estimate only the CERN (Switzerland) needs several thousands of magnetostable photomultipliers.
This development is promising since basic constructions will be created on the basis of which new developments could be effectively realized.
Potential role of foreign participants.
In activities on the Project collaborators take part that is specialists of interested foreign institutes and research centers:
T. Camporcsi (Geneva, Switzerland, CERN );
G. Martellotti (Rome, Italy, Institute Nationale di Fisica);
Prof. B.A. Brill (Worcester, USA, University of Massachusetts);
Prof. S. Askienazy (Paris, France, University/Hospital Saint Antoine).
The Project executors are interested in establishing of contacts with all other organizations which would contribuate to succesful development of works on the Project.
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