Sealed operation, and circulation and purification of gas in the HARPO TPC

HARPO is a time projection chamber (TPC) demonstrator of a gamma-ray telescope and polarimeter in the MeV-GeV range, for a future space mission. We present the evolution of the TPC performance over a five month sealed-mode operation, by the analysis of cosmic-ray data, followed by the fast and complete recovery of the initial gas properties using a lightweight gas circulation and purification system.Comment: Proceedings_MPGD2015, EPJ Web of Conference

Measurement of 1.7 to 74 MeV polarised gamma rays with the HARPO TPC

Current {\gamma}-ray telescopes based on photon conversions to electron-positron pairs, such as Fermi, use tungsten converters. They suffer of limited angular resolution at low energies, and their sensitivity drops below 1 GeV. The low multiple scattering in a gaseous detector gives access to higher angular resolution in the MeV-GeV range, and to the linear polarisation of the photons through the azimuthal angle of the electron-positron pair. HARPO is an R&D program to characterise the operation of a TPC (Time Projection Chamber) as a high angular-resolution and sensitivity telescope and polarimeter for {\gamma} rays from cosmic sources. It represents a first step towards a future space instrument. A 30 cm cubic TPC demonstrator was built, and filled with 2 bar argon-based gas. It was put in a polarised {\gamma}-ray beam at the NewSUBARU accelerator in Japan in November 2014. Data were taken at different photon energies from 1.7 MeV to 74 MeV, and with different polarisation configurations. The electronics setup is described, with an emphasis on the trigger system. The event reconstruction algorithm is quickly described, and preliminary measurements of the polarisation of 11 MeVphotons are shown.Comment: Proceedings VCI201

MIMAC : A micro-tpc matrix for directional detection of dark matter

Directional detection of non-baryonic Dark Matter is a promising search strategy for discriminating WIMP events from background. However, this strategy requires both a precise measurement of the energy down to a few keV and 3D reconstruction of tracks down to a few mm. To achieve this goal, the MIMAC project has been developed. It is based on a gaseous micro-TPC matrix, filled with CF4 and CHF3. The first results on low energy nuclear recoils (H, F) obtained with a low mono-energetic neutron field are presented. The discovery potential of this search strategy is discussed and illustrated by a realistic case accessible to MIMAC.Comment: 6 pages, Proc. of the fifth international symposium on large TPCs for low energy rare event detection, Paris, France, Dec. 2010. To appear in Journal of Physic

The LBNO long-baseline oscillation sensitivities with two conventional neutrino beams at different baselines

The proposed Long Baseline Neutrino Observatory (LBNO) initially consists of $\sim 20$ kton liquid double phase TPC complemented by a magnetised iron calorimeter, to be installed at the Pyh\"asalmi mine, at a distance of 2300 km from CERN. The conventional neutrino beam is produced by 400 GeV protons accelerated at the SPS accelerator delivering 700 kW of power. The long baseline provides a unique opportunity to study neutrino flavour oscillations over their 1st and 2nd oscillation maxima exploring the $L/E$ behaviour, and distinguishing effects arising from $\delta_{CP}$ and matter. In this paper we show how this comprehensive physics case can be further enhanced and complemented if a neutrino beam produced at the Protvino IHEP accelerator complex, at a distance of 1160 km, and with modest power of 450 kW is aimed towards the same far detectors. We show that the coupling of two independent sub-MW conventional neutrino and antineutrino beams at different baselines from CERN and Protvino will allow to measure CP violation in the leptonic sector at a confidence level of at least $3\sigma$ for 50\% of the true values of $\delta_{CP}$ with a 20 kton detector. With a far detector of 70 kton, the combination allows a $3\sigma$ sensitivity for 75\% of the true values of $\delta_{CP}$ after 10 years of running. Running two independent neutrino beams, each at a power below 1 MW, is more within today's state of the art than the long-term operation of a new single high-energy multi-MW facility, which has several technical challenges and will likely require a learning curve.Comment: 21 pages, 12 figure

A FABRY-PEROT CAVITY FOR COMPTON POLARIMETRY

A new kind of Compton polarimeter using a resonant Fabry—Pe« rot cavity as a power buildup for the photon beam is proposed. A prototype of such a cavity is described, along with the results obtained in terms of source to be used in a Compton scattering polarimeter. ( 1998 Elsevier Science B.V. All rights reserved

Long-Baseline Neutrino Facility (LBNF) and Deep Underground Neutrino Experiment (DUNE) Conceptual Design Report Volume 2: The Physics Program for DUNE at LBNF

The Physics Program for the Deep Underground Neutrino Experiment (DUNE) at the Fermilab Long-Baseline Neutrino Facility (LBNF) is described

Shell structure of the neutron-rich isotopes Co 69,71,73

The structures of the neutron-rich Co69,71,73 isotopes were investigated via (p,2p) knockout reactions at the Radioactive Isotope Beam Factory, RIKEN. Isotopes of interest were studied using the DALI2 γ-ray detector array combined with the MINOS target and tracker system. Level schemes were reconstructed using the γ-γ coincidence technique, with tentative spin-parity assignments based on the measured inclusive and exclusive cross sections. Comparison with shell-model calculations using the Lenzi-Nowacki-Poves-Sieja LNPS and PFSDG-U interactions suggests coexistence of spherical and deformed shapes at low excitation energies in the Co69,71,73 isotopes. The distorted-wave impulse approximation (DWIA) framework was used to calculate the single-particle cross sections. These values were compared with the experimental findings