LEAD PERCHLORATE AS A NEUTRINO DETECTION MEDIUM
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LEAD PERCHLORATE AS A NEUTRINO DETECTION MEDIUM STEVEN ELLIOTT, PETER DOE, HAMISH ROBERTSON, TOM STEIGER, JOHN WILKERSON. UNIVERSITY OF WSHINGTON, SEATTLE LEA D PERCH LO RAT E A S A N EU TRINO D ETECT ION M ED IUM LEAD IS AN EXCELLEN T N EUT RINO TAR GET : ♦ H IGH CR OS S SEC T IO N (Fu ller et al. A stro-p h /9 80 916 4 ) ♦ RE LA T IVELY LO W C O ST ♦ CC AND N C REA C T IONS ν e + 208 Pb → 208 Bi ∗ + e ↓ 208 − Y Bi + X γ + Yn ν e + 208 Pb → 208 Pb ∗ + ν ' x ↓ 208 - Y Pb + X γ + Yn D ETECTOR SH OU LD BE SEN SIT IVE T O : ♦ CHA RG ED PAR TICLES ♦ N EU T RO N S ♦ GA MM A RAYS C HARG ED CU RR ENT NEU T R A L CU RR ENT Pb Bi 0 6 12 18 24 MeV 1n 2n 1n 2n 3n 1st GT IAS LEVEL SCHEMES of the 208 Pb 208 Bi System THE NUCLEAR PHYSICS OF LEAD PROPERTIES OF A LEAD PERCHLORATE SOLUTIONS LEAD CERENKOV DETECTOR? Attenuation Length =43c 3 4 5 6 7 8 9 10 11 12 15 35 55 Path Length (cm 1.3 1.35 1.4 1.45 1.5 1.55 0 20 40 60 80 Concentration (% by mass 0 10 20 30 40 50 60 70 80 90 100 200 300 400 500 600 700 Wavelength (nm) D ETE C T OR SH OU LD BE SEN SIT IVE T O : ♦ CHA RG ED PAR TICLES ♦ N EU T RO N S ♦ GA MM A RAYS LEAD PERCHLOR AT E Pb(ClO 4 ) 2 IS: ♦ H IGHL Y SOL U BLE 500g m Pb(C lO 4 ) 2 /100gm H 2 O D ensity = 2.7 @ 80 % Con c. ♦ C ONTA IN S CH LO R INE N eutron Ca ptu re on C l ⇒ 8.4 M eV γ’s 35 C l n captu re cross section 44 .0b ♦ RE LA T IVELY IN EXPEN SIV E ≈$10 k/Tonne (≥ 100 tonne @ 80 % con c.) ♦ A PPEA RS TRAN SPA RE NT R efractive Index = 1.5 @ 80 % Con c. M ay be used as a Cerenkov D etector ♦ W A TER BA SED SOL U TION G ood neutron m od erator 1.7 x 10 21 208 Pb /cc (80% soln .) 3.6 x 10 22 H /cc (80% soln .) Expect about 185 /cm Stopping Power 0.2 cm/MeV (80%) 0.33 cm/MeV (50%) 15 MeV electron ~550 (80%) ~920 (50%) No Obvious Features Scattering or Absorption? Suspect limit due to Pb salt colloids possibly due to reaction with dissolved gases Need to understand chemistry better measurements in progress INDEX OF REFRACTION AS A FUNCTION OF SOLUTION CONCENTRATION SPECTRAL TRANSMISSION THROUGH A 1 CM CELL OF 80% Pb 4 (ClO 4 ) 2 (UNPURIFIED) REFERENCED TO H 2 O ATTENUATION LENGTH OF 430 nm LIGHT IN 80% Pb 4 (ClO 4 ) 2 (UNPURIFIED) APPLICATIONS Transition ν Spectrum σ FHM σ KL Pb(ν e ,e)x T ν =4 MeV η=3 6.9 6.7 Pb(ν e ,e)x T ν =8 MeV η=0 58 43 Pb(ν,ν’ )x T ν =4 MeV η=3 0.66 0.23 Pb(ν,ν’ )x T ν =8 MeV η=0 4.5 1.4 Pb(ν,e)x m DAR 91 59.6 FHM: Fuller, Haxton, McLaughlin, PR D5 9, 085005 (1999) KL: Kolbe, Langanke, preprint Nucl-th\0003060 σ units 10 -40 cm 2 CROSS SECTION COMPARISON Isotope σ ν capture (b) Relative νum . deν. w.r.t. Pb ν capture rate w.r.t. H 204 Pb 0.70 0.01 0 206 Pb 0.03 0.24 0 207 Pb 0.70 0.22 0.04 208 Pb 0.02 0.52 0 35 Cl 44.00 1.52 18.3 37 Cl 0.43 0.48 0.06 16 O 0.00 13.57 0 17 O 0.23 0.01 0 18 O 0.00 0.03 0 H 0.32 11.3 1 n capture time ~10-100 ms. NEUTRON CAPTURE TIME IN 80 % Pb(ClO 4 ) 2 SUPERNOVA OBSERVATORY ν PHYSICS, OSCILLATIONS Conclusions Approximately thermal. Absolute temperature scales are somewhat uncertain. Relative temperature scales are not: there is a hierarchy, T e < T anti-e < T m,t . Observation of T e > T anti-e would be indicative of ν oscillations. Supernova Spectra 2.76 MeV 6.27 MeV 0.1 1 10 100 1000 100 0 Eνery (MeV) 0.1 1 10 100 1000 100 0 Eνery (MeV) Cross Section The cross section is strongly dependent on T e 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 ν e . In coinc., 1-n events are due to ν e and anti- ν e . Spectral Features Ratio for 2-n/1-n Events This ratio is very sensitive to T e . 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-ν e . A DAR m measurement in Pb(ClO 4 ) 2 studies the Pb reaction, without interference from the well known H A 10 t detector could measure the cross section to 10% or so in a few months at proposed ORLaND fac Need to Measure σ 0.1 1 10 100 1000 60 40 20 0 Energy (MeV) Look for 29.8-MeV ν e coming early in time. t p = 26 ns tm = 2200 ns p + ⇒ m + + ν m m + ⇒ e + + ν e + ν μ Oscillations Decay at Rest 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(ClO 4 ) 2 has the potential to make these measurements because it is sensitive to charged particles, gammas 8 6 4 2 8 6 4 2 Electron Anti-Neutrino Temperature (Me 1.7 1.3 0.9 0.5 0.5 0.1 0.1
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LEVEL SCHEMES of the 208 Pb 208 Bi 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. - PowerPoint PPT Presentation
Transcript of LEAD PERCHLORATE AS A NEUTRINO DETECTION MEDIUM
LEAD PERCHLORATE AS A NEUTRINO DETECTION MEDIUMSTEVEN ELLIOTT, PETER DOE, HAMISH ROBERTSON, TOM STEIGER, JOHN WILKERSON. UNIVERSITY OF WSHINGTON, SEATTLELEAD PERCHLORATE AS A NEUTRINO DETECTION MEDIUMSTEVEN ELLIOTT, PETER DOE, HAMISH ROBERTSON, TOM STEIGER, JOHN WILKERSON. UNIVERSITY OF WSHINGTON, SEATTLE
LEAD PERCHLORATEAS A
NEUTRINO DETECTION MEDIUM
LEAD I S AN EXCELLENT NEUTRINO TARGET:
♦ HIGH CROSS SECTION (Fu lle r et al. Ast r o-ph / 980 916 4)
♦ RELATIV ELY LOW COST
♦ CC AND NC REACTIONS
νe
+
208
Pb →
208
Bi
∗
+ e
↓
208 − Y
Bi + X γ + Yn
νe
+
208
Pb →
208
Pb
∗
+ ν
'
x
↓
208 - Y
Pb + X γ + Yn
DETECTOR SHOU LD BE SENSITIVE TO:
♦ CHARGED P ARTICLES
♦ NEUTRONS
♦ GAMM A RAYS
CHARGED CURRENT
NEU TRAL CURRENT
LEVEL SCHEMESof the
208Pb 208Bi System
THE NUCLEAR PHYSICS OF LEADTHE NUCLEAR PHYSICS OF LEAD PROPERTIES OF A LEAD PERCHLORATE SOLUTIONSPROPERTIES OF A LEAD PERCHLORATE SOLUTIONS
LEADCERENKOVDETECTOR?
Attenuation Length =43cm
3
4
5
6
7
8
9
10
11
12
15 35 55
Path Length (cm)
PMT Signal (mA)
1.3
1.35
1.4
1.45
1.5
1.55
0 20 40 60 80
Concentration (% by mass)
Index of Refraction
0
10
20
30
40
50
60
70
80
90
100
200 300 400 500 600 700
Wavelength (nm)
Transmission (%)
DETECTOR SHOULD BE SENSITIVE TO:
♦ CHA RGED PARTI CLES
♦ NEUTRONS
♦ GAMM A RAYS
LEAD PERCHLORAT E Pb(ClO4)2 IS:
♦ HIGHLY SOLUBLE500g m Pb(ClO4) 2/1 00g m H2ODen si t y = 2.7 @ 80 % Con c.
♦ CONTA INS CHLORIN ENeut ron Capt u r e on Cl ⇒ 8 .4 MeV γ’s35 Cl n capt u r e cr oss sect ion 44 .0b
♦ RELATIV ELY INEXPENSIVE≈$10 k / Tonne (≥ 100 tonne @ 80 % con c.)
♦ APPEARS TRANSPARENTRef r act i ve Index = 1.5 @ 80 % Con c.May be u sed as a Cer en kov Detector
♦ WATER BASED SOLUTIONGood ne ut ron m od era tor1.7 x 10 21 208 Pb / cc (80% soln .)3 .6 x 10 22 H / cc (80% soln .)
Expect about 185 /cmStopping Power 0.2 cm/MeV (80%) 0.33 cm/MeV (50%)15 MeV electron ~550 (80%) ~920 (50%)
No Obvious Features
Scattering or Absorption?
Suspect limit due to Pb salt colloids possibly due to reaction with dissolved gasesNeed to understand chemistry better measurements in progress
INDEX OF REFRACTION AS A FUNCTIONOF SOLUTION CONCENTRATION
SPECTRAL TRANSMISSION THROUGH A 1 CM CELL OF 80% Pb4(ClO4)2 (UNPURIFIED) REFERENCED TO H2O
ATTENUATION LENGTH OF 430 nm LIGHT IN 80% Pb4(ClO4)2 (UNPURIFIED)
APPLICATIONS
Transition ν Spectrum σFHM σKL
Pb(νe,e)x Tν=4 MeVη=3
6.9 6.7
Pb(νe,e)x Tν=8 MeVη=0
58 43
Pb(ν,ν’)x Tν=4 MeVη=3
0.66 0.23
Pb(ν,ν’)x Tν=8 MeVη=0
4.5 1.4
Pb(n, )e x μ DAR 91 59.6
FHM: Fuller, Haxton, McLaughlin, PR D59, 085005 (1999)KL: Kolbe, Langanke, preprint Nucl-th\0003060
σ units10-40 cm2
CROSS SECTION COMPARISON
Isotope σ n captur e(b) Relativ e num.den. .w r. .t Pb
n captu re rate.w r. .t H
204Pb 0.70 0.01 0206Pb 0.03 0.24 0207Pb 0.70 0.22 0.04208Pb 0.02 0.52 0
35Cl 44.00 1.52 18.337Cl 0.43 0.48 0.0616O 0.00 13.57 017O 0.23 0.01 018O 0.00 0.03 0
H 0.32 11.3 1
n capture time~10-100 μs.
NEUTRON CAPTURE TIME IN 80 % Pb(ClO4)2
SUPERNOVA OBSERVATORYSUPERNOVA OBSERVATORY ν PHYSICS, OSCILLATIONSν PHYSICS, OSCILLATIONS
ConclusionsConclusions
Approximately thermal.Absolute temperature scales are somewhat uncertain.Relative temperature scales are not: there is a hierarchy, Te < Tanti-e < Tμ,.Observation of Te > Tanti-e would be indicative of ν oscillations.
Supernova Spectra
2.76 MeV 6.27 MeV
0.1
1
10
100
1000
dσ
/ (10dE
-40
cm2
/ )MeV
1000 ( )Energy MeV
fν
0.1
1
10
100
1000
dσ
/ (10dE
-40
cm2
/ )MeV
1000 ( )Energy MeV
fν
Cross Section
The cross section is strongly dependent on Te
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 νe.
In coinc., 1-n events are due to νe and anti- νe.
Spectral Features Ratio for 2-n/1-n Events
This ratio is verysensitive to Te.
FHM indicates uncertainty of 50%.KL and FHM differ by large amounts.Decay at Rest (DAR) μ from stopped + decay has spectrum similar to supernova, but with no anti-νe.A DAR μ 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.
Need to Measure σ
0.1
1
10
100
1000
Cross Section (10
-40
cm2
/MeV)
6040200
Energy (MeV)
fν
Look for 29.8-MeVνe coming early in time. = 26 ns
μ = 2200 ns
+ ⇒ μ+ + νμ
μ+ ⇒ e+ + νe + νμ
OscillationsDecay at Rest
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 thesemeasurements because it is sensitiveto charged particles, gammas and neutrons.
8
6
4
2
Electron Neutrino Temperature (MeV)
8642Electron Anti-Neutrino Temperature (MeV)
2.1
1.7 1.3
0.9
0.5 0.5
0.1 0.1
