LENS:Measuring the

Neutrino Luminosity of the Sun

R. S. RaghavanVirginia Tech

Henderson Capstone DUSEL WorkshopStony Brook University

May 5, 2006

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;

LENS-Sol / LENS-Cal Collaboration(Russia-US: 2004-)

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

“Very Super” Neutrino Beam from the Sun

Solar Neutrinos

• Standard Solar Model

• Missing e (Cl, Ga, SK, SNO)

• Flavor mixing happens (SNO)

• Leads naturally to New Era of precision measurements and tests

What we know:

Critical Test if All solar energy is nuclear: Neutrino luminosity = Photon Luminosity

Experimental status after 40 y of solar nu’s–

No useful constraint for critical test of Neutrino physics or solar astrophysics!

Solar Luminosity: Neutrino vs. Photon

37.06.01

2.03.0nu) from (inferred 4.1/ hh LL

Three main contributions: pp 0.9257Be 0.075

8B 0.00009

Solar Luminosity: Neutrino vs. Photon

Accent of future test of nu luminosityon• Individual fluxes of LOW ENERGY Neutrinos especially pp neutrinos• Direct spectroscopy• PRECISION Fluxes• No direct pp neutrinos so far• New Experiments needed

Measuring Neutrino Luminosity Measuring pp, and other low energy neutrinos

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

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

LENS-Indium: SCIENCE GOAL

SneeIne115

s)4.76( tagdelayedsignalsolar

115 )/(

Precision Measurement of the Neutrino Luminosity of the Sun

• 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 , is this truealso for ?

• RSFP/ Nu magnetic moments Time Variation of pp and 7Be signals? (No Var. of 8B nus !)

(Chauhan et al JHEP 2005)

NEW SCIENCE - Discovery Potential of LENSAPS Nu Study 2004 Low Energy Solar Nu Spectrum: one of 3 Priorities

In the first 2 years (no calibration with -source needed):

e

Low Energy Neutrinos:

Only way to answer these questions !e

New Science from Relative Fluxes

MSW-LMA Profile

Non-standard interactions

Mass-varying neutrinos

Deviations from standard survival probability in various new scenarios

eeP

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)

NEW SCIENCE - Discovery Potential of LENSIn 5 years (with - source calibration):

Tag: Delayed emission of (e/)+ Threshold: 114 keV pp-’s115In 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 signalsnot affected by Indium-Bgd!

LENS-Indium: Foundations

CC -capture in 115In to excited isomeric level in 115Sn

LENS-Sol Signal =

SSM(low CNO) + LMAx

Detection Efficiency

pp: = 64% 7Be: = 85% pep: = 90%

Rate: pp 40 /y /t In 2000 pp ev. / 5y ±2.5% Design Goal: S/N ≥ 3

Expected Result: Low Energy Solar -Spectrum

Access to pp spectral Shape for

the first time

Signal electron energy (= Eν – Q) (MeV)

Coincidence delay time μs

Tag Delayed coincidenceTime Spectrum

Signal area

BgdS/N = 1

S/N = 3

Fitted Solar Nu Spectrum(Signal+Bgd) /5 yr/10 t In

Indium Bgd

S/N=3pp

7Be

pepCNO

7Be*

In-LENS: Studied Worldwide Since 1976!Dramatic Progress in 2005

( MPIK Talk at DPG 03/2004)

Cubic Lattice Non-hybrid (InLS only)

InLS: 8% In, L(1/e)>10m, 900 pe/MeV Mass InLS : 125t to 190tIn: 10t-15t for 1970 pp ’s /5yPMTs: 13,300 (3”) - 6,500 ( 5”)pp- Detection Efficiency: 64-45% S/N ~3 (ALL Indium decay modes)

Status Fall 2003 Status Fall 2005

• In Liq. Scint.

• New Design• Bgd Structure• New Analysis Strategy

Longit. modules + hybrid (InLS + LS)

InLS: 5% In, L(1/e)=1.5m, 230 pe/MeVTotal mass LS: 6000 tIn: 30t for 1900 pp ’s /5y PMTs: ~200,000pp- Detection Efficiency: ~20%S/N~1 (single decay BS only) ~1/ 25 (All In decay modes)

1. Indium concentration ~8%wt (higher may be viable)2. Scintillation signal efficiency (working value): 9000 h/MeV3. Transparency at 430 nm: L(1/e) (working value): 10m4. Chemical and Optical Stabililty: at least 2 years5. InLS Chemistry - Robust

Basic US Patent for metal (In, Sn, Rare Earths…).loading in scint liquids(RSR+EC Bell Labs 2004 )

1

10

100

1000

10000

0 50 100 150 200 250

8% InLS (PC:PBD/MSB) 10800 hν / MeV

BC505 Std12000 h/MeV

In 8%-photo

Light Yield from Compton edgesof 137Cs -ray Spectra

-0.005

0.000

0.005

0.010

0.015

0.020

0.025

0.030

350 390 430 470 510 550 590 630 670 (nm)

Nor

m.

Abs

orba

nce

in 1

0 cm

L(1/e)(InLS 8%) ~ L(PC Neat) !

ZVT39: Abs/10cm ~0.001;

L(1/e)(nominally) >>20 m

InLS

PC Neat

Indium Liquid Scintillator

Milestones unprecedented in metal LS technology

LS technique relevant to many other applicationse.g. reactor nu expts for θ13

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

Test of transparent double foilmirror in liq. @~2bar

New Detector Concept -The Scintillation Lattice Chamber

Light propagationin GEANT4

Concept

Light loss by Multiple Fresnel Reflection

4x4x4m CubeAbsorption length = 10m

Upper limit ~1700pe/MeV (L=10m) - reach via antireflective coating on films?

Adopt1020 pe/MeV7.5 cm cells

Photoelectron yield versus number of cells:

100 keV event in 4x4x4m cube, 12.5cm cellsPerfect 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

Foil Surface Roughness andImpact on the Hit Definition

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 E() -114 keV (e1)

116 keV (g2)

498 keV (g3)

115In

SIGNAL115In

115Sn

β0 + n (BS) (Emax = 499 keV)

498 keV

*Cattadori et al: 2003

β1 (Emax< 2 keV)(b = 1.2x10-6)*

115Sn

e/

Multiple 115In decays simulate tag candidate in many ways

Indium Radioactivity Background

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: 2 β-decays (x10-8)Type C: 3 β-decays (x10-16) Type D: 4 β-decays (x10-24)

Background categories

Strong suppression via energy

Suppression via tag topology

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)

Indium Background Simulations and Analysis

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

Final Result: Overall Background suppresion > 1011

At the cost of signal loss by a factor ~ 1.6

Tag analysis must suppress Background by ~2x104

Sufficient to generate ~4x106 n-tuples for the analysis

Background Suppression - Analysis of Tag Candidates

Signal

/y /t In

Bgd tot

/y /t In

Bgd A1

/y /t In

Bgd A2

/y /t In

Bgd B

/y /t In

RAW 62.5 79 x 1011

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 0.57 4.5 293

+Tag topology 40 13 ± 0.6 0.57 4.0 8.35

“Free”

Cuts

Scintillator properties:

• InLS: 8% In• L(1/e) = 1000cm• LY (InLS) = 9000 h/MeV

Detector Design:

Typical LENS-Sol Design Figures of Merit –Work in Progress

Cell Size

mm

Cube size

m

Pe yield

/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”)

PMTPassiveShield Mirror

InLS

LS Envelope

5m

12m

PMTPassiveShield Mirror

InLS

LS Envelope

5m

PMTPassiveShield Mirror

InLS

LS Envelope

InLS

LS Envelope

5x5x5m

12m

. CagesegmentationOpt.

LENS

Design Concept(not to scale)125 ton InLS10 t Indium13000 3” PMT’s

5” PMTPassiveShield Mirror 5” PMTPassiveShield Mirror

Opt segmentation cage

InLS500 mm

InLS

LS Envelope

500 mm

• InLS : 128 L

• PC Envelope : 200 L

• 12.5cm pmt’s : 108

MINILENS--Prototype

Final Test detectorfor LENS

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 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

“Proxy” pp- events in MINILENS

Next StepTest of all the concepts and the technology developed so far:

MINI-LENS - 130 liter InLS scintillation lattice detector

Summary

● 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

Major breakthroughs:

IN SIGHT: Simple Small LENS (~10 t In /125 t InLS)

Large (50-100kT) Liquid Scintillation Detector

For keV-GeV Multidisciplinary Science

HYPER SCINTILLATION DETECTOR

HSD

HSD100 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 establishedMinus: -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

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) Mostly Crustal Layer2) Fission Reactor ?? Inner Core3) Man-made Power Reactors 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 NUSL

Long Literature: Problem: G. Elders (1966) G. Marx (1969)Detection methods; Krauss et al Nature 310 191 1984 (and ref therein)...many others

Terrestrial Radiogenic Energy Sources Location

1) Radioactivity of U and Th (and others) Mostly Crustal Layer2) Fission Reactor ?? Inner Core3) Man-made Power Reactors 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

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

Borexino 300t

Eurasian Crust

American Crust

Pacific Crust

Atlantic Crust Kamland 1kT

Continental crust 35kmU 1.8ppm; Th 7.2ppm

Oceanic crust 6.5kmU 0.1ppm; Th 0.4 ppm

Total Heat 40TW(U+Th)Heat = 15TWNew: GeoReactor=3-10TW ?

Overall Geo Model: U,Th (Mantle) = U, Th (Crust);

Hawaii

2900 km

6400 km

South PoleGeomanda

R

CORE

MANTLEU 0.01ppmTh 0.04ppm

Total U: 8.2x1019 gTotal Th: 33x1019 g

Internal Energy Sources in the Earth and their Distribution

Kimballton (100 kT)

Borexino 300t

Eurasian Crust

American Crust

Pacific Crust

Atlantic Crust Kamland 1kT

Continental crust 35kmU 1.8ppm; Th 7.2ppm

Oceanic crust 6.5kmU 0.1ppm; Th 0.4 ppm

Total Heat 40TW(U+Th)Heat = 15TWNew: GeoReactor=3-10TW ?

Overall Geo Model: U,Th (Mantle) = U, Th (Crust);

Hawaii

2900 km

6400 km

South PoleGeomanda

R

CORE

MANTLEU 0.01ppmTh 0.04ppm

Total U: 8.2x1019 gTotal Th: 33x1019 g

Internal Energy Sources in the Earth and their Distribution

Kimballton (100 kT)

Homestake 4850’Henderson MC South Pole(Amanda/ice3)

HomestakeHenderson

Power reactors

Possible Nuclear Reactor Background Sources for HMSTK & Hndrsn

(RSR et al PRL 80 (635) 1998)

Aug 2005—NewGlimpse of U/ThBump in Kamland!

Birth of NeutrinoGeophysicsSituation like 1964in solar Neutrinos

(RSR hep-ex/0208038a0

Reactor bgd/Kt/yr

Kamioka: 775Homestake: 55WIPP: 61San Jacinto: 700Kimballton: ~100

LENS-Sol 3.75kT(Lower ReactorBgd )

1kT--

Super Nova Relic (Anti) Neutrino Sensitivity (Strigari et al)

LENS-Sol 3.75kT(Lower ReactorBgd )

1kTLENS-Sol 3.75kT(Lower ReactorBgd )

1kT--

Super Nova Relic (Anti) Neutrino Sensitivity (Strigari et al)

Low Energy Sensitivityis KEY for:

•High Rates•Access to HIGH red Shift part

Detect νMe with tag.

Solar pp

CO, Ne)

Si

Odrziwolek et alAstro-ph/0405006

20 Msun Star at 1kpc

Pre SN ν emission from20Msun Star via pairAnnihilation

• Insensitive to particles below Cerenkovthreshold

• Poor energy resolution

• Hi water solubility of most things –ultrapurity hard

• Low light levels require many PMT’s

PROTON DECAY SEARCH

Typical Cerenkovthresholds

• 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 T1 GeV(elastic scatter)

Why look beyond Cerenkov?

• Insensitive to particles below Cerenkovthreshold

• Poor energy resolution

• Hi water solubility of most things –ultrapurity hard

• Low light levels require many PMT’s

PROTON DECAY SEARCH

Typical Cerenkovthresholds

• 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 T1 GeV(elastic scatter)

Why look beyond Cerenkov?

• 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

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

Limitations from Cerenkov Threshold

• 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

K± are visible in scintillatorGold-plated triple tag

K+) = 12.8 ns T(K) =105 MeVK± 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

K± are visible in scintillatorGold-plated triple tag

K+) = 12.8 ns T(K) =105 MeVK± μ+ ν (63.5%) K± T(μ+ = 152 MeV): eV

EM shower= 135 MeV e s) eV)

e+s)

Major Motivation for Scintillation for p-decay

Efficiency for prominent modesincreases by x8-10 in Scint vs C

Instead of 1 Megaton water Cerenkov Detector use 100 kiloton Scintillation detector (e.g. HSD)

• 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)

HSD enables search for Mode-free Nucleon Decay

Conclusions:• HSD will be a Major Science Opportunity• Top notch multi-disciplinary science justifying cost (~300M?)1. Geophysics 2. SN physics and cosmology3. 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 opportunitiesFor Scintillation based detectors LENS and HSDThatBetween them cover a large swath of top class Science