Study on the intrinsic detection efficiency of scintillator/Cherenkov detector for monitoring 14MeV neutrons by using foil activation method

A neutron detector, based on scintillator and Cherenkov detector, was designed to monitor the D-T neutron generator in a PGNAA online measurement system in our previous study. In this paper, the foil activation method was used to study the intrinsic detection efficiency of the detector to the D-T neutron generator. The Fe foil with 99.99% purity was selected as the activation foil. The experiments and the GEANT4 simulations were carried out to study the intrinsic detection efficiency of the monitor. The results show that the intrinsic detection efficiency of the monitor is 20.42% ± 0.76%. Then, the calibrated detector and Fe foils were simultaneously used to measure the neutron flux of D-T neutron generator. The relative deviation between the results of the two methods is 5.64%.

Searches for exotica and dark matter with neutrino telescopes

Neutrino telescopes are designed to search for neutrino sources in the Universe, exploiting the Cherenkov light emitted along the path of the charged particles produced in interactions occurring close to the detector volume. Their huge size and the shield offered by large water or ice overburden make them excellent tools to search for exotic and rare particles in the cosmic radiation. In particular, they are sensitive to particles not predicted by the Standard Model that could be messenger of new physics. An overview of the experimental scenario and the relevant results obtained looking for magnetic monopoles, dark matter candidates and other exotic relic particles with neutrino telescopes is given, together with the description of possible new perspectives. This article is part of a discussion meeting issue 'Topological avatars of new physics'.

Candidates to Replace R-12 as a Radiator Gas in Cherenkov Detectors

Dichlorodifluoromethane (R-12) has been widely used as a radiator gas in pressure threshold Cherenkov detectors for high-energy particle physics. However, that compound is becoming unavailable due to the Montreal Protocol. To find a replacement with suitably high refractive index, we use a combination of theory and experiment to examine the polarizability and refractivity of several non-ozone-depleting compounds. Our measurements show that the fourth-generation refrigerants R-1234yf (2,3,3,3-tetrafluoropropene) and R-1234ze(E) (trans-1,3,3,3-tetrafluoropropene) have sufficient refractivity to replace R-12 in this application. If the slight flammability of these compounds is a problem, two nonflammable alternatives are R-218 (octafluoropropane), which has a high Global Warming Potential, and R-13I1 (trifluoroiodomethane), which has low Ozone Depletion Potential and Global Warming Potential but may not be sufficiently inert.

Designing a new type of neutron detector for neutron and gamma-ray discrimination via GEANT4

Design of a new type of neutron detector, consisting of a fast neutron converter, plastic scintillator, and Cherenkov detector, to discriminate 14-MeV fast neutrons and gamma rays in a pulsed n-γ mixed field and monitor their neutron fluxes is reported in this study. Both neutrons and gamma rays can produce fluorescence in the scintillator when they are incident on the detector. However, only the secondary charged particles of the gamma rays can produce Cherenkov light in the Cherenkov detector. The neutron and gamma-ray fluxes can be calculated by measuring the fluorescence and Cherenkov light. The GEANT4 Monte Carlo simulation toolkit is used to simulate the whole process occurring in the detector, whose optimum parameters are known. Analysis of the simulation results leads to a calculation method of neutron flux. This method is verified by calculating the neutron fluxes using pulsed n-γ mixed fields with different n/γ ratios, and the results show that the relative errors of all calculations are <5%.