Design optimization of liquid scintillator cosmic-ray veto detector with BBQ shifter Page: 2 of 4
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DESIGN OPTIMIZATION OF LIQUID SCINTILLATION COSMIC RAY VETO DETECTOR
WITH BBQ SHIFTER
rt. W. Kruse
Los Alamos National Lab ratory
P.C. Box 1663, Los Alamos. NM E75**5
S. S. Egdorf and D. F. Simmons
EG4G/North Las Vegas Facility
316 E. Atlas Circle, North Las Vegas, NV 8OO3I
Certain design characteristics cf a liquid
jclntillator detector For charged cosmic particles,
have been studied. These Include evaluation of
scintillator emission spectra, absorption In various
thicknesses 01 BBQ shifter bars and effective
transmission in ior.6 lengths of BBQ acrylic. For our
BBQ sample, 1 <?. 5 rm thick with semicircular shape, thr
shifted light was transit i tted with 2.0 m absorption
Object 1 ve
A large volume liquid scintillation detector is to
be used for neutrino oscillation experiments1.
Detection of various cosmic events is imperative for
background rejection to be accomplished during the
data reduction . It is plained to detect charged
cosmic events by a veto counter that surrounds the
central detector volume (UU70 liter central volume
with 2000 liter in the veto).
Our objective for the effort described here, was
to obtain pertinent data leading to decisions for the
choice of various component parameters affecting the
detection efficiency of the veto detector. Such
parameters Included the scintillator solutes to best
match the BBQ shifter^ and the type of reflector,
Associated studies were mrde of the absorption In
various thicknesses of BBQ and transmission In long
lengths of BBQ waveshlfter bars.
The veto counter features (clgs, 1 and 2 wer-
chosen because of a desire to 1) provide thrrr
electrically independent signals due to cosmic events
to oe delected In the top, bottom, and sides of the
detector. 2) minimize the total voltxne to be used by
phot omul 11 p 1 ler detection, thereby reducing cist of
the drilled hole l.,lo which the detector was .c. be
placed, and 3) to emnorn 17* the cost for
photox.iult ip] ler tubes.
Sc 1 nt 1 1 1 ator Emission Spectra
The la-ge vclune aspects of the detector led to a
ch;lce of p-xylene as the scintillator solvent from a
desire Tor high light ou put, good transmission
( prel inlna^y measurement s Indicate IS m absorption
leng’h for light produced by R particles), pulse shape
discrimination capability and low cost.
Two solutes were evaluated: I) p-terpheny, and
popup ( 1 , U-d 1-2-(S-phen y 101 aiol y 1 ) benzene) because of
economy and 2) ' ityl-PBD (7 g/l) because it 1: more
readily soluble and has better spectral match 10 BBQ.
Ttie emission sper ,ftr from these scintillators was
found to depend upon the method of excitation (sof. 1
rays, ultraviolet light, and Co gaitmns) and luMhe-
studies were restricted to Co gamma radiation since
tha. more closely approximates cosmic muor excitation.
Measured emission .spectra are contained in T'e. 3.
Fig. 1. Schematic of detector and veto regions. The
out JMioSt dimensions are 2.3 m din. ar; ! 1." m high.
Fig. 2. Acrylic BBQ scintillator shape. Thickness is
12.6 air. Positions of light sourer for current
measurements are indicated by "X."
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Kruse, H.W.; Egdorf, S.S. & Simmons, D.F. Design optimization of liquid scintillator cosmic-ray veto detector with BBQ shifter, article, October 1, 1981; New Mexico. (https://digital.library.unt.edu/ark:/67531/metadc1099399/m1/2/: accessed March 19, 2019), University of North Texas Libraries, Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.