T. Enqvist

Large underground, liquid based detectors for astro-particle physics in Europe: Scientific case and prospects

This document reports on a series of experimental and theoretical studies conducted to assess the astro-particle physics potential of three future large scale particle detectors proposed in Europe as next generation underground observatories. The proposed apparatuses employ three different and, to some extent, complementary detection techniques: GLACIER (liquid argon TPC), LENA (liquid scintillator) and MEMPHYS (water Cherenkov), based on the use of large mass of liquids as active detection media. The results of these studies are presented along with a critical discussion of the performance attainable by the three proposed approaches coupled to existing or planned underground laboratories, in relation to open and outstanding physics issues such as the search for matter instability, the detection of astrophysical neutrinos and geo-neutrinos and to the possible use of these detectors in future high intensity neutrino beams.

The next-generation liquid-scintillator neutrino observatory LENA

Abstract As part of the European LAGUNA design study on a next-generation neutrino detector, we propose the liquid-scintillator detector LENA (Low Energy Neutrino Astronomy) as a multipurpose neutrino observatory. The outstanding successes of the Borexino and KamLAND experiments demonstrate the large potential of liquid-scintillator detectors in low-energy neutrino physics. Low energy threshold, good energy resolution and efficient background discrimination are inherent to the liquid-scintillator technique. A target mass of 50xa0kt will offer a substantial increase in detection sensitivity. At low energies, the variety of detection channels available in liquid scintillator will allow for an energy – and flavor-resolved analysis of the neutrino burst emitted by a galactic Supernova. Due to target mass and background conditions, LENA will also be sensitive to the faint signal of the Diffuse Supernova Neutrino Background. Solar metallicity, time-variation in the solar neutrino flux and deviations from MSW–LMA survival probabilities can be investigated based on unprecedented statistics. Low background conditions allow to search for dark matter by observing rare annihilation neutrinos. The large number of events expected for geoneutrinos will give valuable information on the abundances of Uranium and Thorium and their relative ratio in the Earth’s crust and mantle. Reactor neutrinos enable a high-precision measurement of solar mixing parameters. A strong radioactive or pion decay-at-rest neutrino source can be placed close to the detector to investigate neutrino oscillations for short distances and sub-MeV to MeV energies. At high energies, LENA will provide a new lifetime limit for the SUSY-favored proton decay mode into kaon and antineutrino, surpassing current experimental limits by about one order of magnitude. Recent studies have demonstrated that a reconstruction of momentum and energy of GeV particles is well feasible in liquid scintillator. Monte Carlo studies on the reconstruction of the complex event topologies found for neutrino interactions at multi-GeV energies have shown promising results. If this is confirmed, LENA might serve as far detector in a long-baseline neutrino oscillation experiment currently investigated in LAGUNA-LBNO.

Production of new neutron-rich isotopes of heavy elements in fragmentation reactions of 238U projectiles at 1A GeV

The production of heavy neutron-rich nuclei has been investigated using cold-fragmentation reactions of {sup 238}U projectiles at relativistic energies. The experiment performed at the high-resolving-power magnetic spectrometer Fragment Separator at GSI made it possible to identify 40 new heavy neutron-rich nuclei: {sup 205}Pt, {sup 207-210}Au, {sup 211-216}Hg, {sup 214-217}Tl, {sup 215-220}Pb, {sup 219-224}Bi, {sup 223-227}Po, {sup 225-229}At, {sup 230,231}Rn, and {sup 233}Fr. The production cross sections of these nuclei were also determined and used to benchmark reaction codes that predict the production of nuclei far from stability.

Production of medium-mass neutron-rich nuclei in reactions induced by Xe 136 projectiles at 1 A GeV on a beryllium target

Production cross sections of medium-mass neutron-rich nuclei obtained in the fragmentation of {sup 136}Xe projectiles at 1 A GeV have been measured with the FRagment Separator (FRS) at GSI. The measured cross sections are compared to {sup 238}U fission yields and model calculations to determine the optimum reaction mechanism to extend the limits of the chart of the nuclides around the r-process waiting point at N=82.

Light nuclides produced in the proton-induced spallation of U-238 at 1-GeV

The production of light and intermediate-mass nuclides formed in the reaction

Experimental investigation of the residues produced in the 136Xe + Pb and 124Xe + Pb fragmentation reactions at 1A GeV

^{1}mathrm{H}+^{238}mathrm{U}

Isotopic and velocity distributions of {sub 83}Bi produced in charge-pickup reactions of {sub 82}{sup 208}Pb at 1A GeV

at 1 GeV was measured at the Fragment Separator at GSI, Darmstadt. The experiment was performed in inverse kinematics, by shooting a 1 A GeV

Multi-pixel Geiger-mode avalanche photodiode and wavelength-shifting fibre-optics readout of plastic scintillator counters for the EMMA underground experiment

^{238}mathrm{U}

EMMA – an underground cosmic-ray experiment

beam on a thin liquid-hydrogen target. A total of 254 isotopes of all elements in the range

Measurements of muon flux in the Pyhäsalmi underground laboratory

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