No Arabic abstract
Micro-TPC, a time projection chamber(TPC) with micro pixel chamber($mu$-PIC) readout was developed for the detection of the three-dimensional fine(sub-m illimeter) tracks of charged particles. We developed a two-dimensional position sensitive gaseous detector, or the $mu$-PIC, with the detection area of 10$times$10 cm${}^{2}$ and 65536 anode electrodes of 400 $mu$m pitch. We achieved the gas gain of over 10000 without any other multipliers. With the pipe-line readout system specially developed for the $mu$-PIC, we detected X-rays at the rate as high as 7.7 Mcps. We attached a drift cage with an 8 cm drift length to the $mu$-PIC and developed a micro-TPC. We measured the basic performances of the micro-TPC and took three-dimensional tracks of electrons. We also developed a prototype of the MeV gamma-ray imaging detector which is a hybrid of the micro-TPC and NaI(Tl) scintillators and confirmed its concept by reconstructing the obtained data.
A micro time-projection-chamber (micro-TPC) with a detection volume of 23*28*31 cm^3 was developed, and its fundamental performance was examined. The micro-TPC consists of a micro pixel chamber with a detection area of 31*31 cm^2 as a two-dimensional imaging device and a gas electron multiplier with an effective area of 23*28 cm^2 as a pre-gas-multiplier. The micro-TPC was operated at a gas gain of 50,000, and energy resolutions and spatial resolutions were measured.
We report on the performance of a micro-TPC with a micro pixel chamber($mu$-PIC) readout for a time-resolved neutron position-sensitive detector(PSD). Three-dimensional tracks and the Bragg curves of protons with energies of around 1 MeV were clearly detected by the micro-TPC. More than 95% of gamma-rays of 511 keV were found to be discriminated by simple analysis. Simulation studies showed that the total track length of proton and triton emitted from the $rm {}^{3}He$(n,p(573 keV))$rm {}^{3}H(191 keV)$ reaction is about 1.2 cm, and that both particles have large energy losses ($rm > 200 keV/cm$) in 1 atm Ar+$rm C_{2}H_{6}(10%)$+${}^{3}$He($< 1%$). These values suit the current performance of the micro-TPC, and we conclude that a time-resolved neutron PSD with spatial resolution of sub-millimeters shall be developed as an application of the micro-TPC.
The measurement of the ionization produced by particles in a medium presents a great interest in several fields from metrology to particule physics and cosmology. The ionization quenching factor is defined as the fraction of energy released by ionisation by a recoil in a medium compared with its kinetic energy. At low energy, in the range of a few keV, the ionization falls rapidly and systematic measurement are needed. We have developped an experimental setup devoted to the measurement of low energy (keV) ionization quenching factor for the MIMAC project. The ionization produced in the gas has been measured with a Micromegas detector filled with Helium gas mixture.
We propose a new imaging gamma-ray detector in the MeV region. By measuring the directions and energies of not only a scattered gamma ray but also a recoil electron, the direction of an incident gamma ray would be essentially reconstructed event by event. Furthermore, one of two measured (zenith and azimuth) angles of a recoil electron gives us an additional redundancy which enables us to reject the background events by kinematic constraints. In order to measure the track of a recoil electron, the micro Time Projection Chamber($mu$-TPC) has been developed, which can measure the successive positions of the track of charged particles in a few hundred micron meter pitch. The $mu$-TPC consists of the new type of a gas proportional chamber: micro PIxel gas Chamber ($mu$-PIC) which is one of wireless gas chambers and expected to be robust and stable. Using this $mu$-TPC and the Anger camera for the detection of a scattered gamma ray, we have obtained the first gamma-ray image by the full reconstruction of the direction of gamma rays event by event.
Gas detectors are one of the pillars of the research in fundamental physics. Since many years, a new concept of detectors, the Micro Pattern Gas Detectors, allows to overcome many of the problems of other types of commonly used detectors, as drift chambers and microstrips, reducing the discharge rate and increasing the radiation tolerance. Among these, one of the most commonly used is the Gas Electron Multiplier. Commonly deployed as fast timing detectors and triggers, due to their fast response, high rate capability and high radiation hardness, they can also be used as trackers. The center of gravity readout technique allows to overcome the limit of the digital pads, whose spatial resolution is constrained by the pitch size. The presence of a high external magnetic field can distort the electronic cloud and affect the spatial resolution. The micro-TPC reconstruction method allows to reconstruct the three dimensional particle position as in a traditional Time Projection Chamber, but within a drift gap of a few millimeters. This method brings these detectors into a new perspective for what concerns the spatial resolution in strong magnetic field. In this report, the basis of this new technique will be shown and it will be compared to the traditional center of gravity. The results of a series of test beam performed with 10 x 10 cm2 planar prototypes in magnetic field will also be presented. This is one of the first implementations of this technique for GEM detectors in magnetic field and allows to reach unprecedented performance for gas detectors, up to a limit of 120 micron at 1T, one of the worlds best results for MPGDs in strong magnetic field. The micro-TPC reconstruction has been recently tested at very high rates in a test beam at the MAMI facility; preliminary results of the test will be presented.