LEAD PERCHLORATE AS A NEUTRINO DETECTION MEDIUM

1. LEVEL SCHEMES of the 208Pb  208Bi System LEAD PERCHLORATE AS A NEUTRINO DETECTION MEDIUM STEVEN ELLIOTT, PETER DOE, HAMISH ROBERTSON, TOM STEIGER, JOHN WILKERSON. UNIVERSITY OF WSHINGTON, SEATTLE THE NUCLEAR PHYSICS OF LEAD PROPERTIES OF A LEAD PERCHLORATE SOLUTIONS ATTENUATION LENGTH OF 430 nm LIGHT IN 80% Pb4(ClO4)2 (UNPURIFIED) CROSS SECTION COMPARISON NEUTRON CAPTURE TIME IN 80 % Pb(ClO4)2 • Suspect limit due to Pb salt colloids possibly due to reaction with dissolved gases • Need to understand chemistry better measurements in progress SPECTRAL TRANSMISSION THROUGH A 1 CM CELL OF 80% Pb4(ClO4)2 (UNPURIFIED) REFERENCED TO H2O LEAD CERENKOV DETECTOR? • No Obvious Features • Scattering or Absorption? s units 10-40 cm2 INDEX OF REFRACTION AS A FUNCTION OF SOLUTION CONCENTRATION n capture time ~10-100 ms. • Expect about 185 /cm • Stopping Power 0.2 cm/MeV (80%) 0.33 cm/MeV (50%) • 15 MeV electron ~550  (80%) ~920  (50%) FHM: Fuller, Haxton, McLaughlin, PR D59, 085005 (1999) KL: Kolbe, Langanke, preprint Nucl-th\0003060 APPLICATIONS SUPERNOVA OBSERVATORY  PHYSICS, OSCILLATIONS Supernova Spectra Cross Section Need to Measure s The cross section is strongly dependent on Te FHM indicates uncertainty of 50%. KL and FHM differ by large amounts. Decay at Rest (DAR) m from stopped p+ decay has spectrum similar to supernova, but with no anti-ne. A DAR m measurement in Pb(ClO4)2 studies the Pb reaction, without interference from the well known H reaction. A 10 t detector could measure the cross section to 10% or so in a few months at proposed ORLaND facility. Approximately thermal. Absolute temperature scales are somewhat uncertain. Relative temperature scales are not: there is a hierarchy, Te < Tanti-e < Tm,t. Observation of Te > Tanti-e would be indicative of n oscillations. 6.27 MeV 2.76 MeV Conclusions Measuring not just the total number of neutrons but the number of events with 1 or 2 neutrons is very powerful. Measuring the electron energy in coincidence with the neutrons permits separation of NC and CC interactions. Pb(ClO4)2 has the potential to make these measurements because it is sensitive to charged particles, gammas and neutrons. Spectral Features Ratio for 2-n/1-n Events NC events produce little energy in coincidence with neutrons. The CC-events will have electron energy in coincidence with neutrons. The CC electron energy can be sorted as to how many neutrons were in coincidence. In coinc., 2-n events are almost all due to ne. In coinc., 1-n events are due to ne and anti- ne. This ratio is very sensitive to Te. Oscillations Decay at Rest Look for 29.8-MeV ne coming early in time. tp = 26 ns tm = 2200 ns