LEAD PERCHLORATE AS A NEUTRINO DETECTION MEDIUM

1
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 lt Tanti-e lt Tm,t. Observation of Te gt 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