Search results for "Image resolution"
showing 10 items of 377 documents
Silicon detectors for forward tracking in ATLAS
1996
Abstract A 12 cm long silicon microstrip detector module with a fan geometry has been designed and constructed. The performance of the detector has been studied in a test beam at CERN. Results are presented on the hit efficiency and the position resolution as a function of position along the strips. With a hit efficiency of 99.5% and a spatial resolution of typically 35 μm the performance of these detectors exceeds that of other candidate technologies for the precision forward tracker of the ATLAS inner detector.
Time-of-flight photoelectron emission microscopy TOF-PEEM: first results
1998
The time structure of the synchrotron radiation at BESSY (Berlin) is used to operate a photoemission electron microscope in a time-of-flight (TOF) mode. The electrons which are emitted from the sample surface with different energies are dispersed in a drift tube subsequent to the imaging optics. The screen of the microscope was replaced by a fast scintillator (tau = 1.4 ns) and the light is detected by an ultra fast gated intensified CCD camera (800 ps gate 1 MHz repetition rate). The resolving power in the energy domain is demonstrated and possible implications on the spatial resolution (chromatic correction) are discussed. Additionally, an improved contrast at very low emission energies i…
UTSW Small Animal Positron Emission Imager
2006
A Small Animal Imager (SAI) for PET has been designed, built, tested in phantoms, and applied to investigations in mice and rats. The device uses principles based on gamma-ray induced scintillation in crossed fiber optic detectors connected to Position Sensitive Photomultiplier Tubes (PSPMT). Each detector consists of an epoxied stack of 28 layers of 135 round 1 mm BCF-10 scintillating plastic fibers. The overlap region forms a 13.5times13.5times2.8 cm3 detector volume. Scintillating light from the fibers is detected by two (X and Y directions) Hamamatsu R-2486 PSPMTs with 16 anode wires in each of two orthogonal directions. A centroid-finding algorithm gives the position of a light cluster…
AX-PET: A novel PET concept with G-APD readout
2012
Abstract The AX-PET collaboration has developed a novel concept for high resolution PET imaging to overcome some of the performance limitations of classical PET cameras, in particular the compromise between spatial resolution and sensitivity introduced by the parallax error. The detector consists of an arrangement of long LYSO scintillating crystals axially oriented around the field of view together with arrays of wave length shifter strips orthogonal to the crystals. This matrix allows a precise 3D measurement of the photon interaction point. This is valid both for photoelectric absorption at 511 keV and for Compton scattering down to deposited energies of about 100 keV. Crystals and WLS s…
Performance of production modules of the Belle II pixel detector in a high-energy particle beam
2021
The Belle II experiment at the Super B factory SuperKEKB, an asymmetric $e^+e^-$ collider located in Tsukuba, Japan, is tailored to perform precision B physics measurements. The centre of mass energy of the collisions is equal to the rest mass of the $\Upsilon(4S)$ resonance of $m_{\Upsilon(4S)} = 10.58\,\rm GeV$. A high vertex resolution is essential for measuring the decay vertices of B mesons. Typical momenta of the decay products are ranging from a few tens of MeV to a few GeV and multiple scattering has a significant impact on the vertex resolution. The VerteX Detector (VXD) for Belle II is therefore designed to have as little material as possible inside the acceptance region. Especial…
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…
Dependency of Energy-, Position- and Depth of Interaction Resolution on Scintillation Crystal Coating and Geometry
2008
Options for optimizing the energy and spatial resolution of gamma-ray imaging detectors based on thick, monolithic crystals shaped like flat-topped pyramids were studied. Monte Carlo simulations were made of the scintillation light transport for evaluating the effect of four parameters on the energy resolution, the spatial resolutions, and the depth of interaction (DOI) resolution of the gamma-ray imaging detector. These four parameters are: the reflectivity of the surface coating; the scatter mean free path; the absorption mean free path of the scintillation light; and the angle that defines the inclination of the sides of the pyramidal frustum. In real detectors, the values for the mean f…
Maximum likelihood positioning for gamma-ray imaging detectors with depth of interaction measurement
2009
Abstract The center of gravity algorithm leads to strong artifacts for gamma-ray imaging detectors that are based on monolithic scintillation crystals and position sensitive photo-detectors. This is a consequence of using the centroids as position estimates. The fact that charge division circuits can also be used to compute the standard deviation of the scintillation light distribution opens a way out of this drawback. We studied the feasibility of maximum likelihood estimation for computing the true gamma-ray photo-conversion position from the centroids and the standard deviation of the light distribution. The method was evaluated on a test detector that consists of the position sensitive …
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…
Triple GEM tracking detectors for COMPASS
2002
The small area tracker of COMPASS, a high-luminosity fixed target experiment at CERN's SPS, includes a set of 20 large-size ($31\times 31\,\cm^2$) Gas Electron Multiplier (GEM) detectors. Based on gas amplification in three cascaded GEM foils, these devices permit to obtain high gain and good spatial resolution even at very high particle fluxes. A two-coordinate projective readout yields, for each track, highly correlated signal amplitudes on both projections, allowing to resolve multiple hits in high occupancy regions close to the central deactivated area of $5\,\cm$ diameter. At the same time the material exposed to the beam is minimized. Splitting the amplification in three cascaded stag…