CROSS SECTION OF ELECTRON ANTINEUTRINO INTERACTION WITH 40AR AND 84KR AND ITS RELEVANCE TO GEONEUTRINO DETECTION

Neutrino can carry information from places that cannot be reached by the usual detection mechanism because it has a very weak interaction with matter. This can be utilized to study the heat flow process inside the earth by using information carried by geoneutrino (electron antineutrino). In this sense, it is important to know the characteristics of neutrino interaction with materials. In this study, the cross-section calculation of the electron antineutrino interaction with Ar-40 and Kr-84 was carried out using computational methods with the help of GENIE software. In the energy range of 0-10 MeV, the dominant interaction between the two materials is the interaction of QES NC and MEC types with an energy threshold of 5,09 MeV. Both Ar-40 and Kr-84 cannot be used as a scintillator material for geoneutrino detection because in the energy range 0-4,4 MeV the cross-sectional value of the CC interaction is 0.

Design and first tests of the S3 detector of reactor antineutrinos

The new experiment S3 devoted to the study of reactor antineutrinos was designed and constructed as a common activity of IEAP CTU in Prague and JINR (Dubna). The S3 detector is a compact, highly segmented polystyrene-based scintillating detector composed of 80 detector elements with a gadolinium neutron converter between elements layers. A positron and a neutron are produced in an inverse beta decay initiated with an electron antineutrino in the detector. A modular multi-channel fast ADC was developed for the data acquisition for the whole 80-channel S3 detector and the 4-channel cosmic veto system. The detector meets very strict safety rules of nuclear power plants and can be installed in a chamber located immediately under the reactor. The close vicinity from the reactor enables to study neutrino properties with a higher efficiency, to investigate neutrino oscillations at short baselines and try to verify the hypothesis of a sterile neutrino. The details of the design and construction of the S3 detector, as well as properties of the modular multi-channel fast ADC system, and first tests of the device are presented.

Calculation of the Neutrino Mass

The determination of the neutrino mass is considered an important milestone in physics and especially in cosmology. Because it is so extraordinarily small, the usual methods for determining the mass of elementary particles fail. After Wolfgang Pauli's prediction of the neutrino in 1930, experimental proof was not possible until 1956, when an electron antineutrino met a proton and produced a positron and a neutron. The Karlsruhe Tritium Neutrino Experiment KATRIN [1.] is intended to determine the neutrino mass with unique accuracy or, if the sensitivity of the measuring technique is not yet sufficient, to further limit its upper limit. A theoretically exact determination of mass is not yet possible. The present publication is dedicated to this topic. Assuming a mass decay in the universe that includes the neutrino mass, a precise calculation method is proposed and subsequently justified. The effects of neutrino splitting from the proton are examined. In a cosmological perspective, further effects that neutrino decay could have on the expansion of space, gravity, dark mass, magnetic monopoles and time are investigated.

Gamma-induced background in the KATRIN main spectrometer

The KATRIN experiment aims to measure the effective electron antineutrino mass $$m_{\overline{\nu }_e}$$mν¯e with a sensitivity of $${0.2}\,{\hbox {eV}/\hbox {c}^2}$$0.2eV/c2 using a gaseous tritium source combined with the MAC-E filter technique. A low background rate is crucial to achieving the proposed sensitivity, and dedicated measurements have been performed to study possible sources of background electrons. In this work, we test the hypothesis that gamma radiation from external radioactive sources significantly increases the rate of background events created in the main spectrometer (MS) and observed in the focal-plane detector. Using detailed simulations of the gamma flux in the experimental hall, combined with a series of experimental tests that artificially increased or decreased the local gamma flux to the MS, we set an upper limit of $${0.006}\,{\hbox {count}/\hbox {s}}$$0.006count/s (90% C.L.) from this mechanism. Our results indicate the effectiveness of the electrostatic and magnetic shielding used to block secondary electrons emitted from the inner surface of the MS.

aCORN: Measuring the electron-antineutrino correlation in neutron beta decay

The aCORN experiment uses a novel asymmetry method to measure the electron-antineutrino correlation (a-coefficient) in free neutron decay that does not require precision proton spectroscopy. aCORN completed two physics runs at the NIST Center for Neutron Research. The first run on the NG-6 beam line obtained the result a = 0.1090 +/- 0.0030 (stat) +/- 0.0028 (sys), the most precise to date. The second run on the new NG-C high flux beam line promises an improvement in precision to ¡ 2%. In addition we show that an improved measurement of the neutrino asymmetry (B-coefficient) can be made using the aCORN apparatus on a highly polarized neutron beam.