The response of a position-sensitive Li-glass scintillator detector to alpha-particles from a collimated Am-241 source scanned across the face of the detector has been measured. Scintillation light ...was read out by an 8 x 8 pixel multi-anode photomultiplier and the signal amplitude for each pixel has been recorded for every position on a scan. The pixel signal is strongly dependent on position and in general several pixels will register a signal (a hit) above a given threshold. The effect of this threshold on hit multiplicity is studied, with a view to optimize the single-hit efficiency of the detector.
We present results on dielectron production in {sup 40}Ar+KCl collisions at 1.76A GeV. For the first time {omega} mesons could be reconstructed in a heavy-ion reaction at a bombarding energy which is ...well below the production threshold in free nucleon-nucleon collisions. The {omega} multiplicity has been extracted and compared to the yields of other particles, in particular of the {phi} meson. At intermediate e{sup +}e{sup -} invariant masses, we find a strong enhancement of the pair yield over a reference spectrum from elementary nucleon-nucleon reactions, suggesting the onset of nontrivial effects of the nuclear medium. Transverse-mass spectra and angular distributions have been reconstructed in three invariant mass bins. In the former unexpectedly large slopes are found for high-mass pairs. The latter, in particular the helicity-angle distributions, are largely consistent with expectations for a pair cocktail dominated at intermediate masses by {Delta} Dalitz decays.
A first comparison has been made between the pulse-shape discrimination characteristics of a novel He-4-based pressurized scintillation detector and a NE-213 liquicl-scintillator reference detector ...using an Am/Be mixed-field neutron and gamma-ray source and a high-resolution scintillation-pulse digitizer. In particular, the capabilities of the two fast neutron detectors to discriminate between neutrons and gamma-rays were investigated. The NE-213 liquicl-scintillator reference cell produced a wide range of scintillation-light yields in response to he gamma-ray field of the source. In stark contrast, clue to the size and pressure of the He-4 gas volume, the He-4-based detector registered a maximum scintillation-light yield of 750 keV(ee) to the same gamma-ray field. Pulse-shape discrimination for particles with scintillation-light yields of more than 750 keV(ee) was excellent in the case of the He-4-based detector. Above 750 keV(ee) its signal was unambiguously neutron, enabling particle identification based entirely upon the amount of scintillation light produced. (C) 2015 The Authors. Published by Elsevier B.V.
The response of a position-sensitive Li-glass scintillator detector to α-particles from a collimated 241Am source scanned across the face of the detector has been measured. Scintillation light was ...read out by an 8 × 8 pixel multi-anode photomultiplier and the signal amplitude for each pixel has been recorded for every position on a scan. The pixel signal is strongly dependent on position and in general several pixels will register a signal (a hit) above a given threshold. The effect of this threshold on hit multiplicity is studied, with a view to optimize the single-hit efficiency of the detector.
The response of a NE-213 liquid-scintillator detector has been measured using tagged neutrons from 2 to 6MeV originating from an Am/Be neutron source. The neutron energies were determined using the ...time-of-flight technique. Pulse-shape discrimination was employed to discern between gamma-rays and neutrons. The behavior of both the fast (35ns) and the combined fast and slow (475ns) components of the neutron scintillation-light pulses were studied. Three different prescriptions were used to relate the neutron maximum energy-transfer edges to the corresponding recoil-proton scintillation-light yields, and the results were compared to simulations. The overall normalizations of parametrizations which predict the fast or total light yield of the scintillation pulses were also tested. Our results agree with both existing data and existing parametrizations. We observe a clear sensitivity to the portion and length of the neutron scintillation-light pulse considered.
The instrument suite of the European Spallation Source Alba-Simionesco, Christiane; Andersen, K.H.; Argyriou, D.N ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
03/2020, Letnik:
957
Journal Article
The instrument suite of the European Spallation Source Alba-Simionesco, Christiane; Andersen, K.H.; Argyriou, D.N ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
03/2020, Letnik:
957
Journal Article
ALICE HLT High Speed Tracking on GPU Gorbunov, S.; Rohr, D.; Aamodt, K. ...
IEEE transactions on nuclear science,
08/2011, Letnik:
58, Številka:
4
Journal Article
Recenzirano
The on-line event reconstruction in ALICE is performed by the High Level Trigger, which should process up to 2000 events per second in proton-proton collisions and up to 300 central events per second ...in heavy-ion collisions, corresponding to an input data stream of 30 GB/s. In order to fulfill the time requirements, a fast on-line tracker has been developed. The algorithm combines a Cellular Automaton method being used for a fast pattern recognition and the Kalman Filter method for fitting of found trajectories and for the final track selection. The tracker was adapted to run on Graphics Processing Units (GPU) using the NVIDIA Compute Unified Device Architecture (CUDA) framework. The implementation of the algorithm had to be adjusted at many points to allow for an efficient usage of the graphics cards. In particular, achieving a good overall workload for many processor cores, efficient transfer to and from the GPU, as well as optimized utilization of the different memories the GPU offers turned out to be critical. To cope with these problems a dynamic scheduler was introduced, which redistributes the workload among the processor cores. Additionally a pipeline was implemented so that the tracking on the GPU, the initialization and the output processed by the CPU, as well as the DMA transfer can overlap. The GPU tracking algorithm significantly outperforms the CPU version for large events while it entirely maintains its efficiency.
.
We present transverse momentum spectra, rapidity distribution and multiplicity of
-hyperons measured with the HADES spectrometer in the reaction Ar(1.76AGeV) + KCl . The yield of
is calculated from ...our previously reported
/(
+
) ratio and compared to other strange particle multiplicities. Employing a strangeness balance equation the multiplicities of the yet unmeasured
-hyperons can be estimated. Finally a statistical hadronization model is used to fit the yields of
, K
+
,
K
0
s
, K
-
,
,
and
. The resulting chemical freeze-out temperature of
T
= (76±2) MeV is compared to the measured slope parameters obtained from fits to the transverse mass distributions of the different particles.
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