Search results for "Computational physics"
showing 10 items of 725 documents
Zeroing in on the initial state — tomography using bulk, jets and photons
2014
One of the unsolved problems in the current 'standard model' of heavy ion physics is the apparent rapid thermalization of QCD matter in the pre-equilibrium stage. While it is challenging to probe this mechanism directly, there are now several observables available which allow tomographic imaging of the initial state geometry, which is expected to carry remnant information of the equilibration mechanism. On the fluid dynamics side, scaled fluctuations in the momentum space anisotropy parameters v_n image the initial eccentricity fluctuations epsilon_n almost directly with only a weak dependence on the details of the fluid dynamical evolution. From a different direction, due to the strong non…
The magnetic shielding for the neutron decay spectrometer aSPECT
2014
Abstract Many experiments in nuclear and neutron physics are confronted with the problem that they use a superconducting magnetic spectrometer which potentially affects other experiments by their stray magnetic field. The retardation spectrometer a SPECT consists, inter alia, of a superconducting magnet system that produces a strong longitudinal magnetic field of up to 6.2 T. In order not to disturb other experiments in the vicinity of a SPECT, we had to develop a magnetic field return yoke for the magnet system. While the return yoke must reduce the stray magnetic field, the internal magnetic field and its homogeneity should not be affected. As in many cases, the magnetic shielding for a S…
Implementation of theP¯ANDA Planar-GEM tracking detector in Monte Carlo simulations
2018
Abstract The P ¯ ANDA experiment at FAIR will be performed to investigate different aspects of hadron physics using anti-proton beams interacting with a fixed nuclear target. The experimental setup consists of a complex series of detector components covering a large solid angle. A detector with a gaseous active media equipped with gas electron multiplier (GEM) technique will be employed to measure tracks of charged particles at forward direction in order to achieve a high momentum resolution. In this work, a full setup of the GEM tracking detector has been implemented in the P ¯ ANDA Monte Carlo simulation package (PandaRoot) based on the current technical and conceptual design, and the exp…
Performance of the cost-effective Planacon ® MCP-PMTs in strong magnetic fields
2020
Abstract We present the behavior of the cost-effective Planacon MCP-PMTs with 25 μ m pore diameter in the presence of axial magnetic fields up to 0.5 T. Having a batch of 62 devices of the same type, two MCP-PMTs were selected and their gain variation measured in different magnetic fields. These two otherwise identical devices satisfied the selection criteria by requiring the lowest (1.15 kV) and one of the highest (1.4 kV) bias voltage values to achieve a given gain. Both MCP-PMTs have a nearly identical tolerance of the strong magnetic field despite the significant difference in the bias voltage. This clarifies the mechanism of the B-field influence on the MCP-PMT gain, emphasizing the im…
Recursive method for computing matrix elements for two-body interactions
2015
A recursive method for the efficient computation of two-body matrix elements is presented. The method consists of a set of recursion relations for the computationally demanding radial integral and adds one more tool to the set of computational methods introduced by Horie and Sasaki [H. Horie and K. Sasaki, Prog. Theor. Phys. 25, 475 (1961)]. The neutrinoless double-$\ensuremath{\beta}$ decay will serve as the primary application and example, but the method is general and can be applied equally well to other kinds of nuclear structure calculations involving matrix elements of two-body interactions.
Radiation tail in electron scattering: Approximations in the calculation and comparison to measurements
1989
Abstract Different approximations to the calculation of the radiation tail in electron scattering experiments are investigated with particular emphasis on problems related to the peaking approximation and to the convolution of the different contributions to the tail. The calculations are compared to measurements on C and W targets.
Neutron detection and γ-ray suppression using artificial neural networks with the liquid scintillators BC-501A and BC-537
2019
Abstract In this work we present a comparison between the two liquid scintillators BC-501A and BC-537 in terms of their performance regarding the pulse-shape discrimination between neutrons and γ rays. Special emphasis is put on the application of artificial neural networks . The results show a systematically higher γ -ray rejection ratio for BC-501A compared to BC-537 applying the commonly used charge comparison method. Using the artificial neural network approach the discrimination quality was improved to more than 95% rejection efficiency of γ rays over the energy range 150 to 1000 keV for both BC-501A and BC-537. However, due to the larger light output of BC-501A compared to BC-537, neu…
Direct Ionization Impact on Accelerator Mixed-Field Soft-Error Rate
2020
We investigate, through measurements and simulations, the possible direct ionization impact on the accelerator soft-error rate (SER), not considered in standard qualification approaches. Results show that, for a broad variety of state-of-the-art commercial components considered in the 65-16-nm technological range, indirect ionization is still expected to dominate the overall SER in the accelerator mixed-field. However, the derived critical charges of the most sensitive parts, corresponding to ~0.7 fC, are expected to be at the limit of rapid direct ionization dominance and soft-error increase.
Study of the background on a ZnS(Ag) alpha counter with a plastic veto detector
2006
Alpha counters based on the scintillation of ZnS(Ag) have been used widely to measure total alpha activity in environmental samples. The main difficulties for this kind of detectors consist of having a reasonable low background, i.e., around 10−3 counts/s. It is assumed that the background comes from natural sources (mainly radon) and there is no contribution from cosmic, beta or gamma rays since the efficiency for these sources is extremely low. However, the study of the background using a thin plastic veto detector shows that the cosmic ray contribution to the alpha background is about 5–50%, whereas the estimated gamma contribution is below 10%. Therefore, this anti-coincidence set-up ca…
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…