Transcript file

LENS—Overview
R. S. Raghavan
Virginia Tech
LONU-LENS Mini Workshop
Oct 14, 2006
Solar Neutrinos-Past & Future
SSM Prediction
Neutrino beams from SUN
•Very Low Energy
•Pure Favor (e)
•Largest Fluxes
•Longest Base Line
•Largest Intervening Mass
•Highest Magnetic Fields
Unique Machine for Exploration of
Neutrino Phenomenology in
Vacuum, Matter & Magnetic Fields
Directly measured so far
The New Frontier
Directly
measured
STATUS:
From High Energy Nus ( 8B & Atmos)
Non-zero Neutrino Mass
Neutrino Flavor Conversion
NEXT…Door open to Explore
New Physics & Astrophysics
• New Quest: Discoveries beyond Oscillations• New Paradigm: Precision Data, solar model independence
• New Frontier: < 2 MeV
Central
Objectives of LENS
Tagged ν –capture reaction in Indium
LENS is the only developed CC real time detector for solar neutrinos
 e 115In  e  115Sn*  2 115Sn
signal
The Indium Low Energy Neutrino Tag
e
7/2 + 1857
B(GT) ~0.01; Q  =1362
 = 231s
e1
115 In(p,n)
 = 4.76 s
B(GT) = 0.17; Q  = 114 (e/)2 115.6 (e/
 = 16 ps
++
9/29/2
115 In ( 95.7%)
 = 6.4x10 14 y
11/2 - 713.6
100.8 (e/  =5.7)
7/2+ 612.8
Eν = Ee + Q
 Complete LE nu spectrum
Lowest Q known 114 keV
access to 95.5% pp nu’s
• Target isotopic abundance ~96%
• Powerful delayed coinc. Tag
Can suppress bgd =1011 x signal
Downside:
= 0.96 )
3/2 + 497.3
•
Bgd from 115In radioactivity to
( pp nu’s only) rate= 1011 x signal
Tools:
1/2 + 0
115 Sn
Unique:
• Specifies ν Energy
•
 3 497.3
 max = 498.8
delay Tag cascade
1. Time & Space coinc. Granularity
(106suppression)
2. Energy Resolution
In betas <500 keV; ∑Tag = 613 keV
3. Other analysis cuts
Indium Solar Neutrino Detection—R&D History
Hi Granularity(~109) --Lo precision pp (3σ)
Tagged pp reaction in Indium RSR-PRL 1976
Bell Labs (rsr, Pfeiffer, Mills)
1976-79 pp
Bell Labs-MIT (rsr, Deutsch)
1979-84 pp
Oxford (Booth)
1978-90 pp
CEA Saclay (Cribier, Spiro)
1979-81 pp
Penn-Coll de France-KEK-BL-TUM 1987-89 Be
Borexino
1989 -
Be
InLS/Plastic Sandwich
Indium β-spectrum
Plastic/Quartz Fiber Scint
Indium Tunnel Diodes
Hybrid TPC/Plastic
InLS (KEK- Suzuki, Inoue)
ν-e-scattering –no tag
Brute force reduction of bgd via
invention of new ultrapurity chemistry
New tgged pp capture reactions—non radioactive targets –RSR-PRL 1997
LENS R&D LNGS-EU-Russia-USA
1999-01
pp
Yb, Gd, Se –YbLS
Lo Granularity (105) —Hi Precision pp (3%) (SNO result ! )
RSR-hep-ph/010605
LENS R&D LNGS--
2001-03
LENS-Sol/CAL
2004-
pp
In InLS
Nu Lum InLS (LENS-Sol)
Plastic Sandwich (LENS-Cal)
•
•
•
Hi Quality InLS Developed
Background Analysis Insights
New Detector Design Invented
0.05
Normalized Absorbance
Major Progress from LENS LNGS LENS Sol
< Towards Hi Precision pp >
Transparency
of InLS
0.04
10/06/05
01/23/06
03/22/06
0.03
05/31/06
0.02
8.6 m after 8
months
0.01
0
-0.01
350
Status
Fall ‘03*
Status
Summer ‘05
Design of Detector
Longitudinal
Modular
Composition
Hybrid: InLS+ pure
LS
In content
Light attenutation L(1/e)
Signal Eff
Pe/MeV
Cubic Lattice
Chamber
Homogeneous:
InLS only
5% >8%
1.5m >10m
230 900
Indium Mass(1900
pp/5y)
30 ton
Total Mass
6000 ton
125 ton
PMT’s
200,000
13,300
Neutrino detection eff.
S/N (β+γ Bremms. Only
(All In decay modes)
10 ton
20% 64%
~1
~0.04
*MPIK talk at DPG
Mtg Berlin 03/04
~75
~3
390
430
470
510
550
590
630
l (nm)
UV/Vis absorbance of zVt45 (pH 6.88) with time
670
Expected Result from LENS
•
Background precisely
and concurrently
measured
• Well resolved low energy
solar nu spectrum –
 pp, 7Be, pep, CNO with
99+% of solar nu flux
 Solar luminosity in nu’s
 pp spectral shape
accessible for first time
pp Spectral Shape New Science Goal
 Directly Probe Temperature Profile of Energy Production in the Sun
by experimentally measuring the Gamov Energy Shift in
pp Fusion (not observed in laboratory so far)
•
Experiments focused so far on fluxes, not (absolute) energies of solar nu’s ---not possible via electron scattering or radiochemistry
 need energy specific CC detection technology -LENS
Energies of neutrinos from Fusion reactions are usually taken from exothermal
energy release (Q value i.e. difference of initial and final masses) e.g.
p + p  d + e+ + νe (420 keV max);
p + e- + p  d + νe(1442 keV)
This does not include the kinetic (Gamov) energy needed to initiate pp fusion
• Gamov Energy E0 (T) is temperature dependent
• E (T) is added to the pp and pep energy spectra weighted by the fraction of
the flux produced at that temperature---E is typically ~5 keV
• i.e. pp425 keV and pep1447 keV
• Can one observe the Gamov shift by measuring pp and pep energies?
If so---we can directly measure the

temperature profile of energy production by pp fusion
q (lab)
keV
+Δ<E>
keV
+δ<E>
keV
+ΔE
keV
+δE
keV
pp
420.2a
3.41b
1.6
5.2c
1.7
pep
1442.2
6.65b
4.54
7Be
861.8
1.29b
0.81
pep
Eo
pp
aMaximum energy; bShift of mean energy of signal spectrum in the
detector, in the case of pp in the energy range <110-340> keV ;
cShift of maximum energy in sun. The E includes likely
systematic errors (see text)
P lab (q,Qs) ~ q2 p W F(Z,W,Qs) (Z= -1 )
Sun:
Psun ( q)   Plab ( q, Qs  E0 (T )) d pp (T )
 pp
Target:
N ( E )dE ~ Psun ( q)WpF ( Z ,W )dq
(Z=50) Sn
σ = 1.63 keV
Fit measured spectrum to Psun leaving q max free
Find δE from repeated trials; compare to predicted
ΔE
Grieb/RSR
hep-ph/0609030
Science from Neutrino Flux Data
Basic Dichotomy in Solar neutrino Research:
Measured Fluxes vs Unknown Original Fluxes in sun
All science interpretations need ORIGINAL fluxes
Usual Practice: Appeal to predictions of Standard Solar Model
How to make inferences completely free of models?
First Breakthrough: Made by SNO in the case of 8B flux
Single solar source 8B
SNO, SK
Measured 8B NC “flavor-blind” fluxoriginal flux in sun
SK CC+NC spectrum –flavor survival independent of energy
Kamland data with ANTINEUTRINOS
LMA
matter conversion at 8B neutrino energies (~10 MeV)
Major Questions:
1) Conclusion assumes CPT invariance. Is This Correct ?–First opportunity to
Test this for NEUTRINOS
2) LMA if true, predicts different type of conversion at LOW ENERGIES
Verify this: Beyond LMA Discovery !
Imperative to test 1) and 2):
Major Questions:
1) CPT invariance for NEUTRINOS
2) LMA prediction of different type of conversion at LOW ENERGIES
3) Deviations from LMA predictions Discovery
Imperative tests
HOW to attack the problem on a model independent basis?
 Model Independent Fluxes at LOW ENERGIES ?
Basic Need:
Fluxes of single sources
Well identified and resolved Spectroscopic data
Removal of precisely measured background
 Requires CC based Low Energy DetectionDeveloped only in LENS
Bgd Est.
Bgd
measured
Scattering Spectrum (CLEAN)
Absorption Spectrum (LENS)
Solar Luminosity from Low Energy Neutrino Flux data from LENS
Use Best Known Neutrino Model (e.g. LMA) to reverse calculate original
Fluxes from measured fluxes of INDIVIDUAL sources:
pp, Be, pep & CNO, constitute 99+% of solar neutrino flux
Calculate Energy by weighting fluxes with coefficients of energy released
in each solar reaction (Bahcall, Phys. Rev C 65 (2002), 025801)
Solar Luminosity in Neutrinos L(ν inferred)
From Solar Constant
Solar Luminosity in Photons L(hν)
Energy Match from two probes:
L(ν inferred) / L(hν) = 1.00
This tests if the neutrino model used is CORRECT
No SSM used; Inference only via measured quantities
Present Status after 40 years of Solar nu research:
L(ν inferred) / L(hν) = 1.4 (+0.2-0.3; 1 σ)( +0.7-0.6; 3σ)
Bahcall & C. Penya-Garay, JHEP 4, 0311 (2003);
R.G.H. Robertson, Prog. Part. Nucl. Phys. 57, 90 (2006) suggests Lν /L (hν) ~1.12±0.2.
Wide Room For Surprises
Neutrinos notorious for Surprises !
New Global Analysis using:
Data from LENS:
• Measured v Fluxes of pp, Be, pep, CNO
Solar Luminosity in Neutrinos
• Temperature of sun via Gamow shift ;
Data from SNO
• 8B flux (CC and NC);
SK data on spectrum
Match to Measured Photon Luminosity by varying ν parameters
(use the temperature shift to test SSM prediction of dependence of
of pp flux on T ( (1-0.08(T/TSSM)-1.1)
J. N. Bahcall & A. Ulmer, Phys. Rev. D53, 4202 (1996).
This global analysis ASSUMES:
1) Nuclear Reactions SOLE source of Sun’s Energy
2) Quasi hydrostatic Equilibrium
 Neutrino Luminosity Now = Photon Luminosity Now from
Energy created 105 years ago
With Precise Model Independent pp, Be,pep fluxes:
Energy Dependence of Survival Probabilities:
Test LMA, NSI, MVA, Measure θ12 Precisely
Be/pp ~5%
pep/pp~9%
LMA
e)
Mass Var. Nu’s
Precision θ12
NSI
Be/pp ~18%
pep/pp~40%
Sterile Nu
Conclusion
LENS TECHNOLOGY INTRODUCES
Recipe for Discovery in
Particle Physics --CPT, NSI, MVN, Θ12 , Θ13 from absolute energy
Astrophysics of Sun –CNO,Hidden sources of energy, Past
Sun vs Present Sun, Temp of pp fusion (test SSM)
A new comprehensive approach for model independence :
Measuring the Solar Luminosity in Neutrinos and
comparing it directly with the Photon Luminosity
LENS-Sol / LENS-Cal Collaboration
(Russia-US: 2004-)
Russia
INR (Moscow):
IPC (Moscow):
INR (Troitsk) I:
II:
I. Barabanov, L. Bezrukov, V. Gurentsov,
V. Kornoukhov, E. Yanovich
N. Danilov, G. Kostikova, Y. Krylov
J. Abdurashitov, V. Gavrin. et al.
V. Betukhov, A. Kopylov, I. Oriachov, E.Solomontin
U. S.:
BNL:
UNC:
ORNL:
Princeton U. :
SCSU:
Virginia Tech:
R. L. Hahn, M. Yeh
A. Champagne
J. Blackmon, C. Rasco, Qinlin Zeng, A. Galindo-Uribarri
J. Benziger
Z. Chang
C. Grieb, J. Link, M. Pitt, R.S. Raghavan, R. B. Vogelaar,