In spite of a large amount of the existing experimental data in the region of low-energy proton- and photon-nuclear interactions, new experimental measurements are still needed to gain insight into a ...number of problems in nuclear physics. Particularly, the stellar nucleo-synthesis, the study of the resonance states of light nuclei, the underlying mechanisms of the (p,n), (p,α) and (γ,p), (γ,n) reactions are of great interest. For this purpose, the possibility of exploitation of existing electron linear accelerator and cyclotron C18/18, which was launch out recently at AANL (Yerevan Physics Institute), are discussed. The upgrade of the existing electron machine and the purchase of a new modern one for the study of the aforementioned nuclear physics problems are presented as well.
Natural antimony targets were irradiated in a 60 MeV bremsstrahlung beam and gamma spectrometric measurements were performed. The goal was to establish the yield of 117mSn, a radionuclide with great ...potential for application in medicine. Considering that 117mSn is predominantly produced through a photonuclear reaction in which an charged particle is emitted (121Sb(γ,p3n)), the yield of this tin isotope is much lower than the yields of several antimony isotopes produced in (γ,xn) reactions. It has been estimated that photonuclear reactions on natural antimony could produce 117mSn activities needed for therapeutic applications, with accelerators having electron currents of the order of mA. For the used bremsstrahlung energy of 60 MeV, it was estimated how much 119mSn activity can be expected when exposing the antimony target.
•Natural Sb targets were exposed to 60 MeV bremsstrahlung.•Yield of 117mSn was determined using gamma spectroscopy.•It is estimated that (γ,xn) reaction can be used for production of 117mSn for medical purpose.
We report on the results of the first search for the production of axion-like particles (ALPs) via Primakoff production on nuclear targets, γA→aA, in the “SRC-CT” experiment using the GlueX detector ...at Jefferson Lab. This search uses an integrated luminosity of 100 pb⋅−1nucleon on a 12C target with a real photon beam of energies 6<Eγ<10.8 GeV, and explores the mass region of 200<ma<450 MeV via the decay a→γγ. This mass range is between the π0 and η meson masses, which enables the use of the measured η meson production rate to obtain absolute bounds on the ALP production with reduced sensitivity to experimental luminosity and detection efficiency. We find no evidence for an ALP, consistent with previous searches in the quoted mass range, and present limits on the effective photon coupling scale of O(1TeV−1). We further find that the ALP production limit we obtain is hindered by the peaking structure of the non-target-related dominant background the in GlueX spectrometer, which we treat by using data on 4He to estimate and subtract it. We comment on how this search can be improved in a future higher-statistics dedicated measurement.
The paper briefly describes the projects for the modernization and modification of the Yerevan Electron Synchrotron ARUS of the A. Alikhanyan National Science Laboratory (Yerevan Physics Institute). ...The described work proposed in different years is of interest related to the discussion of the issue of creating a new accelerator base in Armenia for solving actual applied and fundamental physical problems.
The results of recent years work, performed at the scientific electron linear accelerator LUE-75 of the A.I. Alikhanyan National Science Laboratory (AANL) on accelerator physics and low-energy ...nuclear physics, are briefly described. The operating installation allows varying the beam current and energy over a wide range 10
–18
–10
–5
A and 10–75 MeV, respectively. The experiments were carried out jointly with research groups both from scientific centers in Armenia and other countries. The main directions of research with the use of electron beams of LUE-75 are outlined.
Based on the linear electron accelerator LUE-75 of the A.I. Alikhanyan National Scientific Laboratory a technique for obtaining controlled primary electron beams with an intensity of 10–20 electrons ...per second in the energy range 15–75 MeV for elementary particle detectors calibration was developed and used. Joint work with the V.P. Dzhelepov Laboratory of Nuclear Problems (JINR, Dubna, RF) showed the efficiency of the technique.
The results to increase the rated energy of the linear accelerator of electrons LUE-75 from 50 to 75 MeV are presented. The characteristics of the beam are investigated, and the measured energy ...spectra of the obtained beams are presented in the range of 50–75 MeV at the average intensity up to 10 μA. The modernization of the elements of magnetic optics for the parallel transfer path was performed, and the beam was tracked to the end of the transport channel.
The OLYMPUS Collaboration reports on a precision measurement of the positron-proton to electron-proton elastic cross section ratio, R_{2γ}, a direct measure of the contribution of hard two-photon ...exchange to the elastic cross section. In the OLYMPUS measurement, 2.01 GeV electron and positron beams were directed through a hydrogen gas target internal to the DORIS storage ring at DESY. A toroidal magnetic spectrometer instrumented with drift chambers and time-of-flight scintillators detected elastically scattered leptons in coincidence with recoiling protons over a scattering angle range of ≈20° to 80°. The relative luminosity between the two beam species was monitored using tracking telescopes of interleaved gas electron multiplier and multiwire proportional chamber detectors at 12°, as well as symmetric Møller or Bhabha calorimeters at 1.29°. A total integrated luminosity of 4.5 fb^{-1} was collected. In the extraction of R_{2γ}, radiative effects were taken into account using a Monte Carlo generator to simulate the convolutions of internal bremsstrahlung with experiment-specific conditions such as detector acceptance and reconstruction efficiency. The resulting values of R_{2γ}, presented here for a wide range of virtual photon polarization 0.456<ε<0.978, are smaller than some hadronic two-photon exchange calculations predict, but are in reasonable agreement with a subtracted dispersion model and a phenomenological fit to the form factor data.
Here, we report the total and differential cross sections for $J/\psi$ photoproduction with the large acceptance GlueX spectrometer for photon beam energies from the threshold at 8.2 GeV up to 11.44 ...GeV and over the full kinematic range of momentum transfer squared, $t$. Such coverage facilitates the extrapolation of the differential cross sections to the forward ($t = 0$) point beyond the physical region. The forward cross section is used by many theoretical models and plays an important role in understanding $J/\psi$ photoproduction and its relation to the $J/\psi$-proton interaction. These measurements of $J/\psi$ photoproduction near threshold are also crucial inputs to theoretical models that are used to study important aspects of the gluon structure of the proton, such as the gluon Generalized Parton Distribution (GPD) of the proton, the mass radius of the proton, and the trace anomaly contribution to the proton mass. We observe possible structures in the total cross section energy dependence and find evidence for contributions beyond gluon exchange in the differential cross section close to threshold, both of which are consistent with contributions from open-charm intermediate states.
The HERMES polarized atomic beam source Nass, A.; Baumgarten, C.; Braun, B. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
06/2003, Letnik:
505, Številka:
3
Journal Article
Recenzirano
Odprti dostop
The HERMES atomic beam source is used to provide nuclear polarized hydrogen or deuterium atoms for the HERMES target. The setup including the dissociator, the sextupole magnet system and the ...high-frequency transitions is described. Measurements of the hydrogen intensity of up to
6.4×10
16
atoms/
s
in two hyperfine substates and of the deuterium intensity of up to
5.8×10
16
atoms/
s
in three hyperfine substates are presented. A degree of dissociation of 92.8% for H (94.5% for D) at the entrance of the storage cell and a nuclear polarization of around 0.97 (H) and 0.92 (D) have been found constant within a couple of percent over the whole running period of the HERMES experiment.
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