Search results for " neutron flux"
showing 6 items of 6 documents
Maintenance Operation on AGN-201 “COSTANZA” Nuclear Research Reactor of Palermo University
2015
During operations with AGN-201 “COSTANZA” nuclear research reactor of Palermo University a failure of a compensated boron-lined ionization chamber provided with a measurement channel was highlighted. A maintenance program aimed to verify the operative conditions of all measurement systems was then started. It was easy to identify as cause of the malfunction a seepage of water inside the container of a Westinghouse WL 6377 ion chamber due to a lack of watertight closure. This can be attributed to corrosion of the container due to parasitic currents circulating between the container, the chamber and the reactor tank that acts as electrical ground of the system. In this work we refer over main…
A search for point sources of EeV neutrons
2012
A thorough search of the sky exposed at the Pierre Auger Cosmic Ray Observatory reveals no statistically significant excess of events in any small solid angle that would be indicative of a flux of neutral particles from a discrete source. The search covers from −90◦ to +15◦ in declination using four different energy ranges above 1 EeV (1018 eV). The method used in this search is more sensitive to neutrons than to photons. The upper limit on a neutron flux is derived for a dense grid of directions for each of the four energy ranges. These results constrain scenarios for the production of ultrahigh energy cosmic rays in the Galaxy.
Neutron and gamma-ray radiation fields characterisation in an 241Am-Be irradiator in view of its use as reserach tool
2019
Introduction A neutron irradiation facility based on four 241Am–Be sources, activity of 1.11·1011 Bq each (yield ~7.0 ·106 n s-1), consisting in four source-channels and an irradiation channel placed in a tank filled with light water both as moderator and biological shielding, was realized at DEIM Department. The aim of this work is to evaluate neutron and gamma fluxes in several points inside the irradiation channel, in view of its use as a testing tool in various research activities. For this goal, an experimental measurement campaign was started also to validate Monte Carlo (MCNP5 code) simulation results. Methods Experimental measurements of neutron radiation fields (fast and thermal) w…
EVALUATION OF ENVIRONMENTAL NEUTRON DOSE AT GROUND LEVEL
2021
This work presents the results of two cycles of neutron dose rate measurements realized using an ALNOR 2202D Neutron Dose Rate Meter whose time response is acquired and analyzed through a controlled ORTEC MCS-32 acquisition card in Windows environment. The data obtained have been compared with values from previous experimental surveys and with the data provided by the worldwide main observatories. It has been also verified the influence of the fluctuations in the flux of cosmic rays during the course of a solar cycle. By comparing the realized measurements and the data provided by the cosmic ray monitoring networks it is also possible to obtain a value of ambient dose equivalent rate and ne…
Chlorine loss from polyvinylchloride under neutron irradiation
1997
PVC samples were irradiated for 1 hour with a thermal neutron flux of Φ th =4.71·1011n·cm−2·s−1 and the chlorine lost during irradiation was measured by γ-ray spectrometry. About 15% of loss of chlorine has been observed for untreated samples while samples heated to temperatures of 60 and 80°C for one minute before irradiation have been found to loose about 8% and 3%, respectively. The results indicate an influence of the polymer structure on the release of chlorine.
Neutron flux and gamma dose measurement in the BNCT irradiation facility at the TRIGA reactor of the University of Pavia
2018
Abstract University of Pavia is equipped with a TRIGA Mark II research nuclear reactor, operating at a maximum steady state power of 250 kW. It has been used for many years to support Boron Neutron Capture Therapy (BNCT) research. An irradiation facility was constructed inside the thermal column of the reactor to produce a sufficient thermal neutron flux with low epithermal and fast neutron components, and low gamma dose. In this irradiation position, the liver of two patients affected by hepatic metastases from colon carcinoma were irradiated after borated drug administration. The facility is currently used for cell cultures and small animal irradiation. Measurements campaigns have been ca…