Signatures of the chiral two-pion exchange electromagnetic currents in the 2H and 3He photodisintegration reactions

The recently derived long-range two-pion exchange (TPE) contributions to the nuclear current operator which appear at next-to-leading order (NLO) of the chiral expansion are used to describe electromagnetic processes. We study their role in the photodisintegration of 2H and 3He and compare our predictions with experimental data. The bound and scattering states are calculated using five different parametrizations of the chiral next-to-next-to-leading order (N2LO) nucleon-nucleon (NN) potential which allows us to estimate the theoretical uncertainty at a given order in the chiral expansion. For some observables the results are very close to the predictions based on the AV18 NN potential and the current operator (partly) consistent with this force. In the most cases, the addition of long-range TPE currents improved the description of the experimental data.Comment: 11 pages, 6 figures (35 eps files

Oscillating ultra-cold neutron spectrometer

The energy spectrum of ultra-cold neutrons (UCN) is very often a key point to determine the systematic effects in precision measurements utilizing UCN. The proposed novel method allows the in-situ measurements of the UCN velocity distribution and its time evolution. In addition, the proposed UCN spectrometer can be a handy diagnostic tool for monitoring the UCN spectrum in critical places in the transport system connecting an UCN source with experiments. In this paper, we present the preliminary results from measurements and simulations using the oscillating UCN spectrometer at the PSI UCN source

Studies of Deuteron Breakup Reactions in Deuteron–Deuteron Collisions at 160 MeV with BINA

A rich set of differential cross section of the three-body 2H(d,dp)n breakup reaction at 160MeV deuteron beam energy has been measured over a large range of the available phase space. The experiment was performed at KVI in Groningen, the Netherlands, using the BINA detector. The cross-section data for the breakup reaction have been normalized to the simultaneously measured 2H(d,d)2H elastic scattering cross section. The breakup cross sections obtained for 147 kinematically complete configurations near the quasifree scattering kinematics are compared to the recent approximate calculations for the three-cluster breakup in deuteron–deuteron collisions. The cross sections for 294 kinematic configurations of the quasi-free scattering regime, for which no theoretical calculations exist, are also presented. Besides the three-body breakup, semiinclusive energy distributions for the four-body 2H(d,pp)nn breakup are reported

Contribution of three nucleon force investigated in deuteron-proton breakup reaction

The elastic scattering and deuteron breakup data were collected in the experiment performed at KVI (Groningen) with use of unpolarized deuteron beam with energy of 80 MeV per nucleon, impinging on hydrogen target. The procedure applied to determine total integrated luminosity is presented. The result will be used for normalization of the differential cross section for the deuteron-proton breakup reaction

Search for axionlike dark matter through nuclear spin precession in electric and magnetic fields

We report on a search for ultra-low-mass axion-like dark matter by analysing the ratio of the spinprecession frequencies of stored ultracold neutrons and 199Hg atoms for an axion-induced oscillating electric dipole moment of the neutron and an axion-wind spin-precession effect. No signal consistent with dark matter is observed for the axion mass range 1024 eV ma 10 17 eV. Our null result sets the first laboratory constraints on the coupling of axion dark matter to gluons, which improve on astrophysical limits by up to 3 orders of magnitude, and also improves on previous laboratory constraints on the axion coupling to nucleons by up to a factor of 40

Measurement of differential cross sections for deuteron-proton breakup reaction at 160 MeV

Differential cross sections for deuteron breakup $^{1}H(d, pp)n$ reaction were measured for a large set of 243 geometrical configurations at the beam energy of 80 MeV/nucleon. The cross section data are normalized by the luminosity factor obtained on the basis of simultaneous measurement of elastic scattering channel and the existing cross section data for this process. The results are compared to the theoretical calculations modeling nuclear interaction with and without taking into account the three-nucleon force (3NF) and Coulomb interaction. In the validated region of the phase space both the Coulomb force and 3NF play an important role in a good description of the data. There are also regions, where the improvements of description due to including 3NF are not sufficient

A novel method for measurement of the spin correlation function for relativistic electron pairs produced in Møller scattering

A self-calibrating double-Mott polarimeter is proposed for measurement of the spin correlation function of relativistic electron pairs produced in Møller scattering. The polarization of outgoing electrons (appearing when the beam is polarized) is utilized for calibration of effective analyzing powers in the secondary Mott scattering used for spin analysis. The experiment will measure the newly introduced relative spin correlation function. This new observable can be measured with a significantly better accuracy than the regular spin correlation function in a small scale experiment. It is shown that both the spin correlation function and the relative spin correlation function are theoretically equivalent. A specific experimental data analysis scenario is proposed, which effectively eliminates the systematic effects related to the imperfect geometry and detector efficiency

Search for BSM physics with neutron beta decay in the BRAND project

Neutron and nuclear beta decay correlation coefficients are sensitive to the exotic scalar and tensor interactions hypotheses that are beyond the Standard Model (BSM). The BRAND project aims at a test of the Lorentz structure of weak interaction in neutron decay by precision measurements of yet unexplored transverse polarization of electrons in correlation with the neutron spin and electron and recoil proton momenta. The experiment will simultaneously measure eleven neutron correlation coefficients (a, A, B, D, H, L, N, R, S, U, V), where seven of them (H, L, N, R, S, U and V) depend on the transverse electron polarization. Five of these correlations: H, L, S, U and V were never attempted experimentally before. The expected ultimate sensitivity of the proposed experiment with respect to BSM couplings will be comparable to that of the ongoing and planned correlation measurements in neutron and nuclear beta decays but offers completely different systematics and additional sensitivity to imaginary parts of the scalar and tensor couplings. An overview of the project, physical motivation and applied experimental techniques were reported. The results of the first pilot run of the experiment performed recently using the cold neutron beam line PF1B at the Laue-Langevin Institute, Grenoble, France were presented, with an emphasis on the challenges of the proposed proton detection technique