Search results for "electron density"
showing 10 items of 428 documents
A device to measure the effects of strong magnetic fields on the image resolution of PET scanners
2009
Abstract Very high resolution images can be achieved in small animal PET systems utilizing solid state silicon pad detectors. As these systems approach sub-millimeter resolutions, the range of the positron is becoming the dominant contribution to image blur. The size of the positron range effect depends on the initial positron energy and hence the radioactive tracer used. For higher energy positron emitters, such as Ga 68 and Tc 94 m , which are gaining importance in small animal studies, the width of the annihilation point distribution dominates the spatial resolution. This positron range effect can be reduced by embedding the field of view of the PET scanner in a strong magnetic field. In…
DIRECT PRODUCTION OF PIONIC ATOMS FROM RADIATIVE TRAPPING OF PIONS IN FLIGHT
1992
Abstract The reaction π−A→(πb−A)γ with Tπ=10−30 MeV producing a π− bound in the nucleus is studied to see its viability as an instrument to produce deeply bound pionic atoms in nuclei. We obtain cross sections of the order of tens of μb/ (sr MeV) for the production of the 1s and 2p states of 208Pb and negligible background from radiative pion capture and the other sources. The negligible background expected in the present reaction is unique among all other reactions so far proposed. The cross sections obtained are three orders of magnitude bigger than those in the best electromagnetic reactions previously proposed. The small background, the large cross sections and the present available flu…
A novel Si strip array to investigate reaction and decay mechanisms
2008
Abstract The performance of a novel set-up of double-sided silicon micro-strip detectors (DSSD) developed for the GSI-R3B project (reaction studies with relativistic radioactive beams) is presented. The set-up was used in an experiment aimed at measuring the two-proton decay of 19 Mg. This experiment required to record simultaneously protons and the residual nuclei with good position and energy resolution. Our experimental results show that both protons and heavy ions ranging from Z = 2 up to Z = 12 can be identified with good signal-to-noise ratio and high energy and spatial resolution. This allowed to reconstruct 2- and 3-particle vertices with high precision, opening the possibility to…
New transitions in the $\beta$-decay of $^{36}$Ca
2001
The β-decay of the Tz = - 2 nucleus 36Ca was studied at the LISE3 magnetic spectrometer at GANIL. Two new proton-emitting states have been detected and the other nine known βp and βγ transitions have been remeasured with improved resolution. A simulation with the GEANT code has been applied to this experimental setup. A comparison with shell model calculations is given.
Resolution, efficiency and stability of HPGe detector operating in a magnetic field at various gamma-ray energies
2008
Abstract The use of High Purity Germanium detectors (HPGe) has been planned in some future experiments of hadronic physics. The crystals will be located close to large spectrometers where the magnetic fringing field will not be negligible and their performances might change. Moreover high precision is required in these experiments. The contribution of magnetic field presence and long term measurements is unique. In this paper the results of systematic measurements of the resolution, stability and efficiency of a crystal operating inside a magnetic field of 0.8 T, using radioactive sources in the energy range from 0.08 to 1.33 MeV, are reported. The measurements have been repeated during sev…
Imaging test setup for the coded-mask /spl gamma/-ray spectrometer SPI
2001
The European Space Agency's International Gamma-Ray Astrophysics Laboratory (INTEGRAL) will be launched in 2002. One of its two main instruments is the spectrometer SPI. It uses 19 HPGe detectors to observe the sky in the energy range of 20 keV to 8 MeV with a resolution of /spl Delta/E/E/spl ap/0.2%. Directional information is obtained using a coded mask. The expected angular resolution is about 20, The SPI imaging test setup (SPITS) was built at the Max-Planck-Institut fur Extraterrestische Physik, Germany, to allow experimental verification of the imaging properties of SPI. SPITS consists of a coded hexagonal uniformly redundant array (HURA) mask and two germanium detectors. The mask is …
High-resolution (3He,t) reaction on the double-βdecaying nucleus136Xe
2011
A (${}^{3}\text{He},t$) charge-exchange reaction experiment on the double-beta decaying nucleus ${}^{136}$Xe has been performed at an incident energy of 420 MeV with the objective to measure the Gamow-Teller (GT) strength distribution in ${}^{136}$Cs. The measurements have been carried out at the dispersion-matched WS beam line and the Grand Raiden spectrometer of the Research Center for Nuclear Physics in Osaka, where an energy resolution of 42 keV was achieved. A new gas cell with thin windows made of polyethylene naphthalate has been employed as a target. The extracted GT strength distribution is confronted with the rather long $2\ensuremath{\nu}\ensuremath{\beta}\ensuremath{\beta}$ deca…
Laboratory astrophysics and microanalysis with NTD-germanium-based X-ray microcalorimeters
2000
With the ability to create cosmic plasma conditions in the laboratory it is possible to investigate the dependencies of key diagnostic X-ray lines on density, temperature, and excitation conditions that exist in astrophysical sources with X-ray optics and a high-resolution X-ray microcalorimeter. The same instrumentation can be coupled to scanning electron microscopes or X-ray fluorescence probes to analyze the elemental and chemical composition of electronic, biological, geological and particulate materials. We describe how our microcalorimeter and X-ray optics provide significantly improved capabilities for laboratory astrophysics and microanalysis.
Study and simulation of the read-out electronics design for a high-resolution plastic scintillating fiber based hodoscope
2015
Abstract This work presents the study and simulation of a high-resolution charged particle detection device for beam positioning, monitoring and calibration, together with its read-out proposal. To provide the precise positional information of the beam, the detection system has been based on Plastic Scintillating Fibers (PSF), while the read-out on a Silicon-PhotoDiode (Si-PD) array. To carry out the study, a PSF prototype with one detection plane has been experimentally tested with a β particle source. Besides, Monte Carlo simulations of the complete system have also been conducted. Both simulations and experimental tests give consistency to the results obtained. The work presented in this…
A prototype of very high resolution small animal PET scanner using silicon pad detectors
2007
Abstract A very high-resolution small animal positron emission tomograph (PET), which can achieve sub-millimeter spatial resolution, is being developed using silicon pad detectors. The prototype PET for a single slice instrument consists of two 1 mm thick silicon pad detectors, each containing a 32×16 array of 1.4×1.4 mm pads readout with four VATAGP3 chips which have 128 channels low-noise self-triggering ASIC in each chip, coincidence units, a source turntable and tungsten slice collimator. The silicon detectors were located edgewise on opposite sides of a 4 cm field-of-view to maximize efficiency. Energy resolution is dominated by electronic noise, which is 0.98% (1.38 keV) FWHM at 140.5…