Development of the MICROMEGAS Detector for Measuring the Energy Spectrum of Alpha Particles by using a 241-Am Source

We have developed MICROMEGAS (MICRO MEsh GASeous) detectors for detecting {\alpha} particles emitted from an 241-Am standard source. The voltage applied to the ionization region of the detector is optimized for stable operation at room temperature and atmospheric pressure. The energy of {\alpha} particles from the 241-Am source can be varied by changing the flight path of the {\alpha} particle from the 241 Am source. The channel numbers of the experimentally-measured pulse peak positions for different energies of the {\alpha} particles are associated with the energies deposited by the alpha particles in the ionization region of the detector as calculated by using GEANT4 simulations; thus, the energy calibration of the MICROMEGAS detector for {\alpha} particles is done. For the energy calibration, the thickness of the ionization region is adjusted so that {\alpha} particles may completely stop in the ionization region and their kinetic energies are fully deposited in the region. The efficiency of our MICROMEGAS detector for {\alpha} particles under the present conditions is found to be ~ 97.3 %

Endothelium-Dependent Vasorelaxant Effect of Prunus Persica Branch on Isolated Rat Thoracic Aorta

Peach (Prunus persica (L.) Batsch) is a popular fruit consumed by people worldwide, owing to its pleasant flavor and high mineral nutrient content. A few plants from the genus Prunus, such as Prunus yedoensis, Prunus cerasus, and Prunus serotina have shown vasorelaxant and vasodilatory effects, to date, no study has investigated the vasorelaxation effects of the P. persica branch extract (PPE). The vasorelaxant effect of PPE was endothelium-dependent, and it was related to the NO-sGC-cGMP, vascular prostacyclin, and muscarinic receptor transduction pathway. K+ channels, such as the BKCa, KV, and KATP channels, were partially associated with PPE-induced vasorelaxation. PPE was effective in relaxing serotonin (5-HT)- or angiotensin II-induced contraction; furthermore, PPE attenuated Ca2+-induced vasoconstriction by IP3 receptors in the SR membrane, but its vasorelaxant effect was not associated with the influx of extracellular Ca2+ via receptor-operative Ca2+ channels or voltage-dependent Ca2+ channels. Recognizing the rising use of functional foods for hypertension treatment, our findings imply that PPE may be a natural antihypertensive agent

Monoenergetic neutrons from the 9Be(p,n)9B reaction induced by 35, 40 and 45-MeV protons

© 2021 Elsevier B.V.The 9Be(p,n)9B reaction was simulated and experimentally conducted in order to test the feasibility of producing monoenergetic neutrons at high energies, for potential uses in various applications. Two distinct peaks of monoenergetic neutrons, well separated by ∼2.4 MeV, were obtained by bombarding a 0.25-mm thick beryllium target with proton beams. For 35, 40 and 45-MeV protons, the corresponding centroid energies of the neutron peaks were (i) 29.4 and 31.8 MeV, (ii) 34.5 and 36.8 MeV, and (iii) 39.7 and 42.0 MeV, respectively. Two approaches were employed for experimental confirmation of the simulated neutron spectra: verification of the known values of the threshold energies of particular (n,xn) reactions, and measurement of the 209Bi(n,4n)206Bi reaction cross section. For verifying the monoenergetic neutrons through the threshold energies, samples of 93Nb, 63Cu and 209Bi were irradiated with neutrons produced by 35, 40 and 45-MeV protons. The measured gamma-ray spectra from the neutron-irradiated samples confirmed the formation of 90Nb, 60Cu and 204Bi radioisotopes and therefore provided evidence that 93Nb(n,4n)90Nb, 63Cu(n,4n)60Cu, and 209Bi(n,6n)204Bi reactions were induced, respectively, by neutrons of 31.8, 36.8, and 42.0 MeV, which are just above the ‘effective’ threshold energies of the respective (n,xn) reactions. In addition, the cross sections of the 209Bi(n,4n)206Bi reaction were measured at 29.4, 31.8, 34.5, 36.8, 39.7 and 42.0 MeV. These newly measured cross sections are close to those predicted by the EAF-2010 and TALYS libraries, which also indirectly verifies the simulated neutron monoenergies. The present studies show that the simulated monoenergetic neutrons can be experimentally reproduced, and their energies can be tailored for applications which require monoenergetic neutrons of different energies.11Nsciescopu

Measurements of cross sections for the

We measured 209Bi(n, 4n) cross sections at neutron energies En = 29.8 ± 1.8 MeV and En = 34.8 ± 1.8 MeV. Bismuth oxide samples were irradiated with the neutrons produced by impinging 30, 35 and 40 MeV proton beams on a 1.05 cm thick beryllium target, where the proton beams were from the MC-50 Cyclotron of Korea Institute of Radiological Medical Sciences (KIRAMS). The neutron flux for each proton beam energy Ep, ΦEp(En), has a broad spectrum with respect to En. By taking the difference in the neutron fluxes, the difference spectra, Φ40(En) −Φ35(En) and Φ35(En) −Φ30(En), are obatined and found to be peaked at En = 29.8 and 34.8 MeV, respectively, with a width of about 3.6 MeV. By making use of this observation and employing the TENDL-2009 library we could extract the 209Bi(n, 4n)206Bi cross sections at the aforementioned neutron energies

Measurements of cross sections for the 209Bi(n, 4n) reaction by using high energy neutrons with continuous energy spectra

We measured 209Bi(n, 4n) cross sections at neutron energies En = 29.8 ± 1.8 MeV and En = 34.8 ± 1.8 MeV. Bismuth oxide samples were irradiated with the neutrons produced by impinging 30, 35 and 40 MeV proton beams on a 1.05 cm thick beryllium target, where the proton beams were from the MC-50 Cyclotron of Korea Institute of Radiological Medical Sciences (KIRAMS). The neutron flux for each proton beam energy Ep, ΦEp(En), has a broad spectrum with respect to En. By taking the difference in the neutron fluxes, the difference spectra, Φ40(En) −Φ35(En) and Φ35(En) −Φ30(En), are obatined and found to be peaked at En = 29.8 and 34.8 MeV, respectively, with a width of about 3.6 MeV. By making use of this observation and employing the TENDL-2009 library we could extract the 209Bi(n, 4n)206Bi cross sections at the aforementioned neutron energies

Measurements of

A proton cyclotron MC-50 in Korea Institute of Radiological & Medical Science (KIRAMS) is used to carry out neutron activation experiments with Y2O3 targets irradiated with neutron beams of a continuous spectrum produced by proton beams on a thick beryllium target. Neutrons are generated by 9Be (p, n) reaction with an incident proton intensity of 20 μA. The neutron spectra generated by proton beams of 30, 35, and 40 MeV are calculated by GEANT4 simulations. Nb powders are used for neutron flux monitoring by measuring the activities of 92mNb through the reaction 93Nb (n, 2n). By using a subtraction method, the average cross section of 89Y(n,2n) and 89Y(n,3n) reactions at the neutron energies of 29.8 ± 1.8 MeV and 34.8 ± 1.8 MeV are extracted and are found to be close to the existing cross sections from the EXFOR data and the evaluated nuclear data libraries such as TENDL-2015 or EAF-2010

Measurements of 89Y(n,2n)88Y and 89Y(n,3n)87Y, 87mY cross sections for fast neutrons at KIRAMS

A proton cyclotron MC-50 in Korea Institute of Radiological & Medical Science (KIRAMS) is used to carry out neutron activation experiments with Y2O3 targets irradiated with neutron beams of a continuous spectrum produced by proton beams on a thick beryllium target. Neutrons are generated by 9Be (p, n) reaction with an incident proton intensity of 20 μA. The neutron spectra generated by proton beams of 30, 35, and 40 MeV are calculated by GEANT4 simulations. Nb powders are used for neutron flux monitoring by measuring the activities of 92mNb through the reaction 93Nb (n, 2n). By using a subtraction method, the average cross section of 89Y(n,2n) and 89Y(n,3n) reactions at the neutron energies of 29.8 ± 1.8 MeV and 34.8 ± 1.8 MeV are extracted and are found to be close to the existing cross sections from the EXFOR data and the evaluated nuclear data libraries such as TENDL-2015 or EAF-2010