133 research outputs found
An Approximation to the Cross Sections of Z_l Boson Production at CLIC by Using Neural Networks
In this work, the possible dynamics associated with leptophilic Z_l boson at
CLIC (Compact Linear Collider) have been investigated by using artificial
neural networks (ANNs). These hypotetic massive boson Z_l have been shown
through the process e+e- -> M+M-. Furthermore, the invariant mass distributions
for final muons have been consistently predicted by using ANN. For these highly
non-linear data, we have constructed consistent empirical physical formulas
(EPFs) by appropriate feed- forward ANN. These ANN-EPFs can be used to derive
further physical functions which could be relevant to studying Z_l.Comment: 9 pages, 8 figure
Systematics on ground-state energies of nuclei within the neural networks
One of the fundamental ground-state properties of nuclei is binding energy.
In this study, we have employed artificial neural networks (ANNs) to obtain
binding energies based on the data calculated from Hartree-Fock-Bogolibov (HFB)
method with the two SLy4 and SKP Skyrme forces. Also, ANNs have been employed
to obtain two-neutron and two-proton separation energies of nuclei. Statistical
modeling of nuclear data using ANNs has been seen as to be successful in this
study. Such a statistical model can be possible tool for searching in
systematics of nuclei beyond existing experimental nuclear data.Comment: 7 pages, 6 figure
An artificial neural network application on nuclear charge radii
The artificial neural networks (ANNs) have emerged with successful
applications in nuclear physics as well as in many fields of science in recent
years. In this paper, by using (ANNs), we have constructed a formula for the
nuclear charge radii. Statistical modeling of nuclear charge radii by using
ANNs has been seen as to be successful. Also, the charge radii, binding
energies and two-neutron separation energies of Sn isotopes have been
calculated by implementing of the new formula in Hartree-Fock-Bogoliubov (HFB)
calculations. The results of the study shows that the new formula is useful for
describing nuclear charge radii.Comment: 7 pages, 3 figure
Identification and rejection of scattered neutrons in AGATA
Gamma rays and neutrons, emitted following spontaneous fission of 252Cf, were
measured in an AGATA experiment performed at INFN Laboratori Nazionali di
Legnaro in Italy. The setup consisted of four AGATA triple cluster detectors
(12 36-fold segmented high-purity germanium crystals), placed at a distance of
50 cm from the source, and 16 HELENA BaF2 detectors. The aim of the experiment
was to study the interaction of neutrons in the segmented high-purity germanium
detectors of AGATA and to investigate the possibility to discriminate neutrons
and gamma rays with the gamma-ray tracking technique. The BaF2 detectors were
used for a time-of-flight measurement, which gave an independent discrimination
of neutrons and gamma rays and which was used to optimise the gamma-ray
tracking-based neutron rejection methods. It was found that standard gamma-ray
tracking, without any additional neutron rejection features, eliminates
effectively most of the interaction points due to recoiling Ge nuclei after
elastic scattering of neutrons. Standard tracking rejects also a significant
amount of the events due to inelastic scattering of neutrons in the germanium
crystals. Further enhancements of the neutron rejection was obtained by setting
conditions on the following quantities, which were evaluated for each event by
the tracking algorithm: energy of the first and second interaction point,
difference in the calculated incoming direction of the gamma ray,
figure-of-merit value. The experimental results of tracking with neutron
rejection agree rather well with Geant4 simulations
Discrimination of gamma rays due to inelastic neutron scattering in AGATA
Possibilities of discriminating neutrons and gamma rays in the AGATA
gamma-ray tracking spectrometer have been investigated with the aim of reducing
the background due to inelastic scattering of neutrons in the high-purity
germanium crystals. This background may become a serious problem especially in
experiments with neutron-rich radioactive ion beams. Simulations using the
Geant4 toolkit and a tracking program based on the forward tracking algorithm
were carried out by emitting neutrons and gamma rays from the center of AGATA.
Three different methods were developed and tested in order to find
'fingerprints' of the neutron interaction points in the detectors. In a
simulation with simultaneous emission of six neutrons with energies in the
range 1-5 MeV and ten gamma rays with energies between 150 and 1450 keV, the
peak-to-background ratio at a gamma-ray energy of 1.0 MeV was improved by a
factor of 2.4 after neutron rejection with a reduction of the photopeak
efficiency at 1.0 MeV of only a factor of 1.25.Comment: Accepted for publication in Nuclear Instruments and Methods in
Physics Research, A, 26 May 2009; 13 pages, 5 tables, 12 figure
Response of AGATA Segmented HPGe Detectors to Gamma Rays up to 15.1 MeV
The response of AGATA segmented HPGe detectors to gamma rays in the energy
range 2-15 MeV was measured. The 15.1 MeV gamma rays were produced using the
reaction d(11B,ng)12C at Ebeam = 19.1 MeV, while gamma-rays between 2 to 9 MeV
were produced using an Am-Be-Fe radioactive source. The energy resolution and
linearity were studied and the energy-to-pulse-height conversion resulted to be
linear within 0.05%. Experimental interaction multiplicity distributions are
discussed and compared with the results of Geant4 simulations. It is shown that
the application of gamma-ray tracking allows a suppression of background
radiation following neutron capture by Ge nuclei. Finally the Doppler
correction for the 15.1 MeV gamma line, performed using the position
information extracted with Pulse-shape Analysis, is discussed.Comment: 10 pages, 11 figure
Conceptual design of the early implementation of the NEutron Detector Array (NEDA) with AGATA
The NEutron Detector Array (NEDA) project aims at the construction of a new high-efficiency compact neutron detector array to be coupled with large (Formula presented.) -ray arrays such as AGATA. The application of NEDA ranges from its use as selective neutron multiplicity filter for fusion-evaporation reaction to a large solid angle neutron tagging device. In the present work, possible configurations for the NEDA coupled with the Neutron Wall for the early implementation with AGATA has been simulated, using Monte Carlo techniques, in order to evaluate their performance figures. The goal of this early NEDA implementation is to improve, with respect to previous instruments, efficiency and capability to select multiplicity for fusion-evaporation reaction channels in which 1, 2 or 3 neutrons are emitted. Each NEDA detector unit has the shape of a regular hexagonal prism with a volume of about 3.23l and it is filled with the EJ301 liquid scintillator, that presents good neutron- (Formula presented.) discrimination properties. The simulations have been performed using a fusion-evaporation event generator that has been validated with a set of experimental data obtained in the 58Ni + 56Fe reaction measured with the Neutron Wall detector array
- …