Transcript LENScapst - Stony Brook NN Group

LENS:
Measuring the
Neutrino Luminosity of the Sun
R. S. Raghavan
Virginia Tech
Henderson Capstone DUSEL Workshop
Stony Brook University
May 5, 2006
LENS-Sol / LENS-Cal Collaboration
(Russia-US: 2004-)
Russia:
INR (Moscow): I. Barabanov, L. Bezrukov, V. Gurentsov,
V. Kornoukhov, E. Yanovich;
INR (Troitsk): V. Gavrin et al., A. Kopylov et al.;
U. S.:
BNL:
A.Garnov, R. L. Hahn, M. Yeh;
U. N. Carolina: A. Champagne;
ORNL:
J. Blackmon, C. Rasco, A. Galindo-Uribarri;
Princeton U. : J. Benziger;
Virginia Tech: Z. Chang, C. Grieb, M. Pitt,
R.S. Raghavan, R.B. Vogelaar;
“Very Super” Neutrino Beam from the Sun
Best part --Free of Charge
For NEUTRINO PHYSICS:
• WELL DEFINED HIGHEST FLUX (pp)
• FLAVOR PURE - νe only
• LONGEST BASELINE
• LARGEST MASS OF HIGH DENSITY
• LOWEST ENERGIES (keV to MeV)
• LOW ENERGY SPECTRUM - ENERGY DEP. EFFECTS
Best tools for investigating neutrino flavor phenomena in
Vacuum and in Matter
For ASTROPHYSICS
Best tool for unprecedented look at how a real Star works
- in the past, present and future
Solar Neutrinos
What we know:
• Standard Solar
Model
• Missing e (Cl,
Ga, SK, SNO)
• Flavor mixing
happens (SNO)
• Leads naturally
to New Era of
precision
measurements
and tests
Solar Luminosity: Neutrino vs. Photon

Critical Test if All solar energy is nuclear:
Neutrino luminosity = Photon Luminosity
Experimental status after 40 y of solar
nu’s–
   
Lh (inferred from nu) / Lh  1.4
0.2
0.7
0.3 1 0.6 3
No useful constraint for critical test of
Neutrino physics or solar astrophysics!
Solar Luminosity: Neutrino vs. Photon
Three main contributions: pp
7Be
8B
0.925
0.075
0.00009
Measuring Neutrino Luminosity  Measuring pp, and other low energy neutrinos
Accent of future test of nu luminosity
on
• Individual fluxes of
LOW ENERGY Neutrinos
especially pp neutrinos
• Direct spectroscopy
• PRECISION Fluxes
• No direct pp neutrinos so far
• New Experiments needed
LENS-Indium: SCIENCE GOAL
Precision Measurement of the Neutrino Luminosity of the Sun
LENS-Sol:
 Measure the low energy solar electron - spectrum
(pp, 7Be, pep, CNO)
 ± ~3% pp-  flux in 5 years of data
 Experimental tool: Tagged CC Neutrino Capture in Indium
 e  In  e  (
 /
e ) 

solar signal
115


delayed tag ( 4.76s)
LENS-Cal:
 Measure precise B(GT) of 115In CC reaction using
MCi 51Cr neutrino source at BAKSAN
 Tagged -capture to specific level of 115Sn
 Note: B(GT) = 0.17 measured via (p,n) reactions
115
Sn
NEW SCIENCE - Discovery Potential of LENS
APS Nu Study 2004 Low Energy Solar Nu Spectrum: one of 3 Priorities
In the first 2 years (no calibration with -source needed):
• Test of MSW LMA physics - no specific physics proof yet !
Pee(pp)=0.6 (vac. osc.) Pee(8B)=0.35 (matter osc.), as predicted?
• Non-standard Fundamental Interactions?
Strong deviations from the LMA profile of Pee(E) ?
• Mass Varying Neutrinos?
(see above)
• CPT Invariance of Neutrinos?
so far LMA only from Kamland e , is this true
also for  e ?
• RSFP/ Nu magnetic moments
Low Energy
Neutrinos:
Only way to
answer these
questions !
Time Variation of pp and 7Be signals? (No Var. of 8B nus !)
(Chauhan et al JHEP 2005)
New Science from Relative Fluxes
Mass-varying neutrinos
MSW-LMA Profile
Non-standard interactions
Deviations from standard P 
e
e
survival probability in various
new scenarios
NEW SCIENCE - Discovery Potential of LENS
In 5 years (with - source calibration):
pp, 7Be -fluxes at earth ±3%  Measured Neutrino Luminosity ~4%
 Ultimate test of the Sun And the Neutrino
 Astrophysics: L > Lh Is the sun getting hotter?
L < Lh Cooling or a sub-dominant non-nuclear
source of energy in the sun?
Test also neutrino physics  because the Lν derivation needs best

known nu parameters
 Precision values of θ12, θ13 (from cos4 θ13 dependence of all fluxes)
 Sterile Neutrinos? ( especially with CC from LENS and NC from

electron scattering)
LENS-Indium: Foundations
CC -capture in 115In to excited isomeric level in 115Sn
Tag: Delayed emission of (e/)+ 
Threshold: 114 keV  pp-’s
115In abundance: ~ 96%
Background Challenge:
• Indium-target is radioactive!
( = 6x1014 y)
• 115In β-spectrum overlaps pp- signal
Basic background discriminator:
Time/space coincidence tag
Tag energy: E-tag = Eβmax +116 keV
7Be,
CNO & LENS-Cal signals
not affected by Indium-Bgd!
Expected Result: Low Energy Solar -Spectrum
LENS-Sol Signal
=
Signal area
Bgd
SSM(low CNO) + LMA
x
Detection Efficiency e
S/N = 1
S/N = 3
Coincidence delay time μs
pp: e = 64%
7Be: e = 85%
pep: e = 90%
 Rate: pp 40 /y /t In
 2000 pp ev. / 5y ±2.5%
 Design Goal: S/N ≥ 3
Access to pp
spectral Shape for
the first time
Tag Delayed coincidence
Time Spectrum
Fitted Solar Nu Spectrum
(Signal+Bgd) /5 yr/10 t In
pp
S/N=3
7Be
Indium Bgd
CNO
pep
7Be*
Signal electron energy (= Eν – Q) (MeV)
In-LENS: Studied Worldwide Since 1976!
Dramatic Progress in 2005

Status Fall 2003
Status Fall 2005
• In Liq. Scint.
• New Design
• Bgd Structure
• New Analysis
Strategy
Longit. modules + hybrid (InLS + LS)
Cubic Lattice Non-hybrid (InLS only)
InLS: 5% In, L(1/e)=1.5m, 230 pe/MeV
Total mass LS: 6000 t
In: 30t for 1900 pp ’s /5y
PMTs: ~200,000
pp- Detection Efficiency: ~20%
S/N~1 (single decay BS only)
~1/ 25 (All In decay modes)
InLS: 8% In, L(1/e)>10m, 900 pe/MeV
Mass InLS : 125t to 190t
In: 10t-15t for 1970 pp ’s /5y
PMTs: 13,300 (3”) - 6,500 ( 5”)
pp- Detection Efficiency: 64-45%
( MPIK Talk at DPG 03/2004)
S/N ~3 (ALL Indium decay modes)
Indium Liquid Scintillator
Milestones unprecedented
in metal LS technology
10000
1000
LS technique relevant to
many other applications
e.g. reactor nu expts for θ13
100
In 8%-photo
10
Light Yield from Compton edges
of 137Cs -ray Spectra
1
0
50
100
150
200
250
0.030
Norm. Absorbance in 10 cm
1. Indium concentration ~8%wt
(higher may be viable)
2. Scintillation signal efficiency
(working value): 9000 h/MeV
3. Transparency at 430 nm:
L(1/e) (working value): 10m
4. Chemical and Optical
Stabililty: at least 2 years
5. InLS Chemistry - Robust
BC505 Std
12000 h/MeV
8% InLS (PC:PBD/MSB)
10800 hν / MeV
Basic US Patent for metal (In, Sn,
Rare Earths…).loading in scint liquids
(RSR+EC Bell Labs 2004 )
L(1/e)(InLS 8%) ~ L(PC Neat) !
0.025
ZVT39: Abs/10cm ~0.001;
0.020
 L(1/e)(nominally) >>20 m
0.015
0.010
InLS
0.005
0.000
-0.005
PC Neat
350
390
430
470
510
550
590
630
l (nm)
670
New Detector Concept The Scintillation Lattice Chamber
Light propagation
in GEANT4
Concept
Test of transparent double foil
mirror in liq. @~2bar
3D Digital Localizability of Hit within one cube
 ~75mm precision vs. 600 mm (±2σ) by TOF in longitudinal modules
 x8 less vertex vol.  x8 less random coinc.  Big effect on Background
 Hit localizability independent of event energy
Light loss by Multiple Fresnel Reflection
Photoelectron yield versus number of cells:
Upper limit ~1700pe/MeV (L=10m) reach via antireflective coating on films?
Adopt
1020 pe/MeV
7.5 cm cells
4x4x4m Cube
Absorption length = 10m
Foil Surface Roughness and
Impact on the Hit Definition
100 keV event in 4x4x4m cube, 12.5cm cells
Perfect optical surfaces : 20 pe (per channel)
Rough optical surfaces : 20% chance of non- ideal optics at every reflection
12 pe in vertex + ~8 pe in “halo”
Conclusion - Effect of non-smooth segmentation foils:
• No light loss - (All photons in hit and halo counted)
• Hit localization accuracy virtually unaffected
Signal Reconstruction
• Event localization relies on
PMT hit pattern (NOT on
signal timing)
• Algorithm finds best solution
for event pattern to match
PMT signal pattern
• System is overdetermined,
hardly affected by
unchannelled light
• Timing information + position
 shower structure
Indium Radioactivity Background-The Final Frontier
BGD
115In
β1 (Emax< 2 keV)
(b = 1.2x10-6)*
E() -114 keV (e1)
115In
β0 + n (BS)
(Emax = 499
keV)
*Cattadori et al: 2003
Multiple 115In
decays simulate
tag candidate in
many ways
e/
116 keV (g2)
498 keV

115Sn
498 keV (g3)
115Sn
SIGNAL
Indium Radioactivity Background
Background categories
115In
–decays in (quasi) prompt RANDOM coincidence produce a tag:
Basic tag candidate: Shower near vertex (Nhit ≥ 3) - chance coincident with
115In β in vertex
Type A:
A1 = β + BS  (Etot = 498 keV) (x1)
A2 =  (498 keV) (x1)
Type B:
Type C:
Type D:
2 β-decays (x10-8)
3 β-decays (x10-16)
4 β-decays (x10-24)
Strong suppression via energy
Suppression via tag topology
Indium Background Simulations and Analysis
Data: Main Simulation of Indium Events with GEANT4
• ~ 4x106 In decays in one cell centered in ~3m3 volume (2-3 days PC time)
• Analysis trials with choice of pe/MeV and cut parameters (5’ /trial)
Analysis Strategy
• Primary selection - tag candidate shower
events with Nhit ≥ 3
• Classify all eligible events (Nhit ≥ 3)
according to Nhit
• Optimize cut conditions individually for
each Nhit class
Main Cuts
• Total energy: g2+g3
• Tag topology: Distance of lone  from
shower
Background Suppression Analysis of Tag Candidates
RAW
Signal
/y /t In
Bgd tot
/y /t In
62.5
79 x 1011
Bgd A1
/y /t In
Bgd A2
/y /t In
Bgd B
/y /t In
“Free”
Valid tag (Energy, Branching,
Shower) in Space/Time
delayed coinc. with prompt
event in vertex
50
2.76 x 105 8.3 x 104 2.8 x 103 1.9 x 105
+ ≥3 Hits in tag shower
46
2.96 x 104 2.6 x 104 2.5 x 103 1.4 x 103
+Tag Energy = 620 keV
44
306
+Tag topology
40
13 ± 0.6
Cuts
0.57
4.5
293
0.57
4.0
8.35
 Tag analysis must suppress Background by ~2x104
 Sufficient to generate ~4x106 n-tuples for the analysis
Final Result: Overall Background suppresion > 1011
At the cost of signal loss by a factor ~ 1.6
Typical LENS-Sol Design Figures of Merit –
Work in Progress
Scintillator properties:
• InLS: 8% In
• L(1/e) = 1000cm
• LY (InLS) = 9000 h/MeV
Detector Design:
Cell
Size
mm
Cube Pe
size yield
m
/MeV
Det
Eff
%
pp-
/t In/y
Bgd
/t In/y
S/N
M
(In)*
ton
M
(InLS)
ton
PMT
75
4
1000
64%
40
13
3
10
125
13300
(3”)
125
5
950
40%
26
9
2.9
15.3
190
6250
(5”)
LENS
LS Envelope
Design Concept
(not to scale)
125 ton InLS
10 t Indium
13000 3” PMT’s
InLS
5x5x5m
5m
Opt. segmentation. Cage
Passive
Shield
Mirror
12m
PMT
MINILENS--Prototype
Final Test detector
for LENS
LS Envelope
• InLS : 128 L
InLS
500 mm
• PC Envelope : 200 L
• 12.5cm pmt’s : 108
Opt segmentation cage
Passive
Shield
Mirror
5” PMT
MINILENS: Global test of LENS R&D
• Test detector technology
Large Scale InLS
Design and construction
• Test background suppression of In
radiations by 10-11
• Demonstrate In solar signal detection
in the presence of high background
Direct blue print for full scale LENS
“Proxy” pp- events in MINILENS
Proxy pp nu events in
MINILENS from cosmogenic
115In(p,n)115Sn isomers
• Pretagged via , p tracks
• Post tagged via n and
230  s delay
 Gold plated 100 keV
events (proxy pp),
Tagged by same cascade
as In- events
 Demonstrate In- Signal
detection even in
MINILENS
Summary
Major breakthroughs:
● In LS Technology
● Detector Design
● Background Analysis
 Basic feasibility of In-LENS-Sol secure
● extraordinary suppression of In background
(all other Bgd sources not critical)
● Scintillation Chamber – InLS only
● High detection efficiency  low detector mass
● Good S/N
IN SIGHT: Simple Small LENS (~10 t In /125 t InLS)
Next Step
Test of all the concepts and the technology developed so far:
MINI-LENS - 130 liter InLS scintillation lattice detector
Large (50-100kT)
Liquid Scintillation Detector
For keV-GeV
Multidisciplinary Science
HYPER SCINTILLATION DETECTOR
HSD
HSD
100 KT LIQUID SCINTILLATION DEVICE?
Next generation device beyond CTF, Borexino, Kamland, LENS…
The technology now has a large worldwide group of experts with
experience/expertise in constructing and operating massive LS
detectors (upto 1 kT so far), for precision low energy (>100 keV )
astro-particle physics
Essential questions for a large scale project like this:
• What science can be achieved that may be unique?
• Can one achieve multidisciplinary functionality?
• Are the possible science questions of first rank impact?
• Can it be competitive with other large scale detector
technologies in science payoff, cost. technical readiness …?
Working Group (Theory and Experiment):
•F.Feilitzsch, L. Oberauer (TU Munich0
•R. Svoboda (LSU)
•Y. Kamyshkov, P. Spanier (U. Tennessee)
•J. Learned, S. Pakvasa (U. Hawaii)
•K. Scholberg (Duke U.)
•M. Pitt, B.Vogelaar, T. Takeuchi, C. Grieb,
Lay Nam Chang, R. S. R (VT)
Bring together earlier work:
• Munich Group -LENA (aimed at a European site)
• R. Svoboda et al
• Y. Kamishkov et al
• RSR
LS Technology (Targets in LS: 12C, p)
Pluses: +Signal x50 that of Cerenkov
+Low Energy (>100 keV) Spectroscopy
(in CTF (5T, 20% PMT coverage) 14C spectrum >30 keV)
+Heavy Particle Detection well below C-threshold
+Tagging of rare events by time-space correlated cascades
+Ultrapurity-ultralow bgds even < 5 MeV (radio “Wall”)
+Technology of massive LS well established
Minus: -Isotropic signal—no directionality
Unique Tool for Anti-Neutrino Physics
==Nuebar tagging by delayed neutron capture by protons
Very low fluxes (~1/cm2/s @5 MeV) conceivable with care and effort:
•Good depth to avoid -n cosmogenics (e.g. 9Li—prefer no heavy
element for n-capture)
• Efficient muon veto of n, std 5m water shield to cut n, PMT, rock 
• Ultrapurity to cut internal  < 5 MeV
• Locate far from high power reactors
Main Topics in Focus
Particle Physics
• Proton Decay
• Long baseline Neutrino Physics—especially with nuebars
Geophysical Structure and Evolution of Earth
•
Global measurement of the antineutrinos from U, Th in
the interior of the earth
• ( Fission Reactor at the center of the earth ??? )
Supernova Astrophysics and Cosmology
•
Supernovae—Real time detection
•
Relic Supernova Spectrum
•
Pre-supernova Pair emission of C,O, Ne or Si burning
Test of present geophysical Models by
First ever measurement of global geophysical
parameters
•radiogenic energy output,
•chemical analysis such as U/Th ratio
•
•geophysical distribution
•discovery of new geophysics
--e.g.core fission reactor
Terrestrial Radiogenic Energy Sources
Location
1) Radioactivity of U and Th (and others)
2) Fission Reactor ??
3) Man-made Power Reactors
Mostly Crustal Layer
Inner Core
Surface
ALL ABOVE SOURCES EMIT ANTINEUTRINOS
• ANTINEUTRINO SPECTROSCOPY CAN PROBE THE EARTH
•
Just as neutrino spectroscopy has probed the Sun
•TECHNOLGY MATURE AND AVAILABLE
•PARASITIC MEASUREMENT IN DETECTORS FOR OTHER PHYSICS
•TIMELY TO CONSIDER FOR DUSEL
NUSL
Long Literature: Problem:
G. Elders (1966) G. Marx (1969)
Detection methods; Krauss et al Nature 310 191 1984 (and ref therein)...many others
Spectroscopy & Specific Model Tests:
Raghavan et al PRL 80 635 1998
Rotschild et al, Geophys. Res. Lett. 25,1083 1998
Internal Energy Sources in the Earth and their Distribution
Total Heat
40TW
(U+Th)Heat = 15TW
New:
GeoReactor=3-10TW ?
Total U: 8.2x10 19 g
Total Th: 33x1019 g
Overall Geo Model:
U,Th (Mantle) = U, Th (Crust);
Borexino 300t
Continental crust 35km
U 1.8ppm; Th 7.2ppm
R
64
Atlantic Crust
Kimballton (100 kT)
American Crust
Homestake 4850’
Henderson MC
South Pole
Geomanda
CORE
MANTLE
U 0.01ppm
Th 0.04ppm
0
Eurasian Crust
m
0k
2900 km
Kamland 1kT
Pacific Crust
Hawaii
Oceanic crust 6.5km
U 0.1ppm; Th 0.4 ppm
South Pole(Amanda/ice3)
Henderson
Homestake
Power reactors
Possible Nuclear Reactor Background Sources for HMSTK & Hndrsn
(RSR et al PRL 80 (635) 1998)
Aug 2005—New
Glimpse of U/Th
Bump in Kamland!
Birth of Neutrino
Geophysics
Situation like 1964
in solar Neutrinos
Reactor bgd/Kt/yr
Kamioka: 775
Homestake: 55
WIPP:
61
San Jacinto: 700
Kimballton: ~100
(RSR hep-ex/0208038a0
Super Nova Relic (Anti) Neutrino Sensitivity
(Strigari et al)
Low Energy Sensitivity
is KEY for:
•High Rates
•Access to HIGH red
Shift part
1kT
LENS-Sol
3.75kT
(Lower ReactorBgd)
Pre SN ν emission from
20Msun Star via pair
Annihilation
C
O, Ne)
Solar pp
Si
Detect ν̃e with tag.
20 Msun Star at 1kpc
Odrziwolek et al
Astro-ph/0405006
PROTON DECAY SEARCH
Why look beyond Cerenkov?
• Insensitive to particles
below Cerenkov
threshold
• Poor energy resolution
• Hi water solubility of most
things –ultrapurity hard
• Low light levels require many
PMT’s
Typical Cerenkov
thresholds
• Electron T=0.262 MeV
• Gamma E=0.421 MeV
(Compton)
• Muon T=54 MeV
• Pion T=72 MeV
• Kaon T=253 MeV
• Proton T=481 MeV
• Neutron T1 GeV
(elastic scatter)
Limitations from Cerenkov Threshold
• No K+ from 2-body nucleon decay can be
seen directly
• many nuclear de-excitation modes not
visible directly
• “stealth” muons from atmospheric neutrinos
serious background for proton decay, relic SN
search
K± are visible in scintillator
Gold-plated triple tag
K+) = 12.8 ns T(K) =105 MeV
K± μ+ ν (63.5%)
K±   
T(μ+ = 152 MeV):
   eV
EM shower= 135 MeV
  e   s)
  eV)
e+   s)
• KamLAND MC for 340
MeV/c K+
• K+ gives over 10,000 p.e.’s
• + gives over 15,000 p.e.’s
• K+/+ separation is possible
• Light curves for first 6
events from KL MC 
Major Motivation for Scintillation for p-decay
Efficiency for prominent modes
increases by x8-10 in Scint vs C
Instead of 1 Megaton water Cerenkov Detector use
100 kiloton Scintillation detector (e.g. HSD)
HSD enables search for Mode-free Nucleon Decay
• Disappearance of n in 12C leads to 20 MeV
excitation of 11C followed by delayed
coincidences at few MeV energy
• This pioneering technique opens the door to a
very different way of looking for nucleon
decay –best facilitated in LS technique
• Kamyshkov and Kolbe (2002)
Conclusions:
•
•
1.
2.
3.
•
•
HSD will be a Major Science Opportunity
Top notch multi-disciplinary science
justifying cost (~300M?)
Geophysics
SN physics and cosmology
Proton/nucleon decay
#1 not possible in any other detector—Uniqueness--Discovery
#2 best served by low energy sensitivity-higher event yields and access to
high red shift cosmology—
best chance for definitive landmark result
#3 better opportunities in HSD than Cerenkov
and at least as good handles as in LAr
Conclusions
Henderson DUSEL offers attractive opportunities
For Scintillation based detectors LENS and HSD
That
Between them cover a large swath of top class Science