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LENS, MINILENS STATUS R. S. Raghavan Virginia Tech For The LENS Collaboration TAUP 07 Sendai, Japan Sep 13, 2007 RaghavanTAUP07-9-12-07 LENSLow Energy Neutrino Spectroscopy Tagged

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SLIDE 1

Raghavan—TAUP07-9-12-07

LENS, MINILENS STATUS

  • R. S. Raghavan

Virginia Tech For The LENS Collaboration TAUP 07 Sendai, Japan Sep 13, 2007

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SLIDE 2

Raghavan—TAUP07-9-12-07

Sn Sn e In

e 115 * 115 115

2 +

  • +
  • +
  • Tagged

signal delay Tag cascade

LENS—Low Energy Neutrino Spectroscopy

R&D Funded now by NSF [ Placed in MUST FUND Category by two Review Panels] LENS is the only CC detector developed to date for low energy solar neutrinos

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SLIDE 3

Raghavan—TAUP07-9-12-07

115In ( 95.7%)

= 6.4x10 14 y

115Sn

B(GT) = 0.17; Q

=114

e1 (e/)2 115.6 (e/ = 0.96 ) 3

497.3

115 In(p,n)

100.8 (e/ =5.7 )

= 4.76 μs max = 498.8 = 16 ps = 231 μs

9/2+ 1/2 + 3/2 + 7/2 + 11/2 - 497.3 612.8 713.6 7/2 + 1857 B(GT) ~0.01; Q

=1362

e

115In ( 95.7%)

= 6.4x10 14 y

115Sn

B(GT) = 0.17; Q

=114

e1 (e/)2 115.6 (e/ = 0.96 ) 3

497.3

115 In(p,n)

100.8 (e/ =5.7 )

= 4.76 μs max = 498.8 = 16 ps = 231 μs

9/2+ 1/2 + 3/2 + 7/2 + 11/2 - 497.3 612.8 713.6 7/2 + 1857 B(GT) ~0.01; Q

=1362

e

The Indium Low Energy Neutrino Tag

115In ( 95.7%)

= 6.4x10 14 y

115Sn

B(GT) = 0.17; Q

=114

e1 (e/)2 115.6 (e/ = 0.96 ) 3

497.3

115 In(p,n)

100.8 (e/ =5.7 )

= 4.76 μs max = 498.8 = 16 ps = 231 μs

9/2+ 1/2 + 3/2 + 7/2 + 11/2 - 497.3 612.8 713.6 7/2 + 1857 B(GT) ~0.01; Q

=1362

e

115In ( 95.7%)

= 6.4x10 14 y

115Sn

B(GT) = 0.17; Q

=114

e1 (e/)2 115.6 (e/ = 0.96 ) 3

497.3

115 In(p,n)

100.8 (e/ =5.7 )

= 4.76 μs max = 498.8 = 16 ps = 231 μs

9/2+ 1/2 + 3/2 + 7/2 + 11/2 - 497.3 612.8 713.6 7/2 + 1857 B(GT) ~0.01; Q

=1362

e

The Indium Low Energy Neutrino Tag

Unique:

  • Specifies
  • LE$NS Detection Scheme
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SLIDE 4

Raghavan—TAUP07-9-12-07

LENS-Sol Signal =

SSM(low CNO) + LMA x 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 (= E – Q) (MeV) Coincidence delay time μs Tag Delayed coincidence Time Spectrum

Signal area

Bgd

S/N = 1 S/N = 3

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

Indium Bgd

S/N=3

pp

7Be

pep CNO

7Be*

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SLIDE 5

Raghavan—TAUP07-9-12-07

Science from LENS—Hi precision low energy Nu fluxes (pp 3-4%) 1.Neutrino Physics –Energy dependence of Pee Oscillation Phenomenology

  • 2. Solar Luminosity vs Photon Lluminosity—

Astrophysics/Neutrino physics

  • 3. Gamow Energy of pp fusion—Energy production

in sun

  • 4. Physics beyond Std model—Sterile Neutrinos from

LENS+Source

  • 5. Solar model independent Fluxes –CC+NC

(LENS + Borexino)

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SLIDE 6

Raghavan—TAUP07-9-12-07

New Technology of LENS Developed in last three years

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SLIDE 7

Raghavan—TAUP07-9-12-07

Technology and Bgd Control

< Towards Hi Precision pp neutrino flux >

  • Hi Quality InLS
  • New Detector Design
  • Background Analysis Insights -115 In decay bgd

suppressed S/N ~3 for first time

UV/Vis absorbance of zVt45 (pH 6.88) with time

  • 0.01

0.01 0.02 0.03 0.04 0.05 350 390 430 470 510 550 590 630 670 (nm) Normalized Absorbance

10/06/05 01/23/06 03/22/06 05/31/06

8.6 m after 8 months

Transparency of InLS

Neutrino detection eff. PMT’s Total Mass Indium Mass(1900 pp/5y) InLS: In content Light attenutation L(1/e) Signal Eff Pe/MeV Design of Detector 64% 13,300 125 ton 10 ton >8% >8m 900 Cubic Lattice Chamber

Status

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SLIDE 8

Raghavan—TAUP07-9-12-07

  • 1. Indium concentration ~8%wt

(higher may be viable)

  • 2. Scintillation signal efficiency

(working value): 8000 h/MeV

  • 3. Transparency at 430 nm:

L(1/e) (working value): 8m

  • 4. Chemical and Optical

Stability: at least 1 year

  • 5. InLS Chemistry – Robust

New = LAB based InLS

Basic Bell Labs Patent,

Chandross, Raghavan

1 10 100 1000 10000 50 100 150 200 250

8% InLS (PC:PBD/MSB) 10800 h / MeV BC505 Std 12000 h/MeV

In 8%-photo

Light Yield from Compton edges

  • f 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)

  • Norm. Absorbance in 10 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 Status

Milestones unprecedented in metal LS technology LS technique relevant to many other applications

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SLIDE 9

Raghavan—TAUP07-9-12-07

3D Digital Localizability of Hit within one cube ~75mm precision vs. 600 mm (±2) 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 double foil mirror in liq. @~2bar

New Detector Technology –hi event position localization The Scintillation Lattice Chamber

Light channeling in 3-d totally Internally reflecting cubic Lattice GEANT4 sim. of concept. Demonstration Acrylic Model

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SLIDE 10

Raghavan—TAUP07-9-12-07

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SLIDE 11

Raghavan—TAUP07-9-12-07

Lattice Structure

Single Foil Double Foil

Solid teflon segmentation Double-layer (air-gap) lattice

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SLIDE 12

Raghavan—TAUP07-9-12-07

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SLIDE 13

Raghavan—TAUP07-9-12-07

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SLIDE 14

Raghavan—TAUP07-9-12-07

Indium --Background Structure – Space / Time coincidence

Signal

E() -114 keV 116 keV 497 keV

115In 115Sn

e/

  • =4.76μs

Background: Random time and space coincidence between two -decays ( ); Extended shower ( ) can be created by: a) 498 keV from decay to excited state; b) Bremsstrahlungs -rays created by ; c) Random coincidence (~10 ns) of more -decays; Or any combination of a), b) and c). Signal Signature: Prompt e- ( )followed by low energy (e-/) ( ) and Compton-scattered ( )

  • >time/space coincidence
  • > tag fixed energy 613keV
  • >compton scattered

shower

115In

0 + n (BS) (Emax = 499 keV) 498 keV 1 (Emax< 2 keV) (b = 1.2x10-6)*

115Sn

  • Bgd
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SLIDE 15

Raghavan—TAUP07-9-12-07 79 x 1011 62.5 RAW rate 13 ± 0.6 40

  • D. +Tag topology

306 44

  • C. +Tag Energy = 614 keV

2.96 x 104 46

  • B. + 3 Hits in tag shower

2.76 x 105 50

  • A. Tag in Space/Time delayed coincidence

with prompt event in vertex Bgd (In) y-1 (t In)-1 Signal (pp) y-1 t In)-1 Results of GEANT4 Monte Carlo simulation (cell size = 7.5cm, S/N=3)

Background rejection steps for pp detection (other neutrinos detected free of Indium background):

  • A. Time/space coincidence in the same cell required

for trigger;

  • B. Tag requires at least three ‘hits’;
  • C. Narrow energy cut;
  • D. A tag topology: multi- vs. Compton shower;

Classification of events according to hit multiplicity; Cut parameters optimized for each event class improved efficiency;

Reduction by ~3.107 through time/space coincidence

Indium --Background Discrimination

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SLIDE 16

Raghavan—TAUP07-9-12-07

  • 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 true also for “neutrinos” ?

  • RSFP/ Nu magnetic moments

Time Variation of pp and 7Be signals? (No Var. of 8B nus !)

(Chauhan et al JHEP 2005)

Neutrino Phenomenology – from LENS

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

e

  • Low Energy

Neutrinos: Only way to answer these questions !

e

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SLIDE 17

Raghavan—TAUP07-9-12-07

Solar Luminosity: Neutrino vs. photon

Will be met under these conditions:

  • 1. Fusion reactions are the sole source of energy production in the sun
  • 2. The sun is in a quasi-steady state (change in 40,000 years is negligible)
  • 3. The neutrino oscillation model is correct & no other physics involved;

From a single detector: Test of astrophysics, solar model; Test of neutrino physics (LMA-MSW at low E, NSI, mass-varying s, 13, …);

Measured neutrino fluxes at earth + oscillation physics nuclear reaction rates energy release in the sun Solar luminosity as measured by photon flux

= ?

inferred

  • L
  • h

L

Energy Balance:

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SLIDE 18

Raghavan—TAUP07-9-12-07

Main contributions: pp 0.91

7Be

0.074 (CNO 0.014)

8B

0.00009

Neutrino inferred Luminosity of the Sun - Experimental Status

Measured neutrino fluxes at the earth:

8B

(SK, SNO) known very well

7Be + 8B

(Cl) sensitive mostly to 8B pp + 7Be + 8B (Ga)

7Be

(Borexino, Kamland – in the future)

in principle can deduce pp- flux Problem: disentangling fluxes from individual neutrino sources

Experimental status – No useful constraint!

( ) ( )

  • 3

7 . 6 . 1 2 . 3 . (inferred)

4 . 1 / =

h

L L

( )

2 . 2 . 1 /

(inferred)

=

  • h

L L

R.G.H.Robertson, Prog. Part. Nucl. Phys. 57, 90 (2006) J.N.Bahcall and C.Peña-Garay, JHEP 0311, 4 (2003)

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SLIDE 19

Raghavan—TAUP07-9-12-07

hep:

Relative kinetic particle energies add to the Q-value of capture and fusion reactions. Not all energies contribute evenly:

3 2

15

91 . 5 T keV E

  • =

Temperature in the Solar Core impacts Neutrino Energies, not just relative fluxes

E0 pep pp

pp- and pep neutrino production temperature and related Gamow peak energy:

7Be electron capture: maxwellian energy

distribution shifts mean energy of 7Be line by <E> ~ 1.29 keV

3 2

) 10 5 . 1 / ( 73 . 10

7

K T keV E

  • =

pp-fusion: Gamow Peak at 5.2 keV pp endpoint shifted up by~5.2keV

J.N. Bahcall, Phys. Rev. D 44(6), 1644(1991)

3 2

) 10 5 . 1 / ( 91 . 5

7

K T keV E

  • =

J.N. Bahcall, Phys. Rev. D 44(6), 1644(1991)

pep: combination, delta <E> ~ 6.6 keV

J.N. Bahcall, Phys. Rev. D 49(8), 3923 (1994)

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SLIDE 20

Raghavan—TAUP07-9-12-07

Probing the Temperature Profile of Energy Production in the Sun with LENS

  • C. Grieb and R.S. Raghavan,

Phys.Rev.Lett.98:141102,200 7

Top:pp- spectrum with/without Gamow shift Bottom: Signal spectrum in LENS with/without Gamow shift 12t Indium - 6years

  • E/E=6% at

300keV Measured Gamow shift in improved LENS: 10000 simulations with ~3000 pp events each =1.62keV

Conclusion: Slightly improved LENS can detect the predicted Gamow shift in the pp- endpoint E=5.2keV with 95% confidence.

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SLIDE 21

Raghavan—TAUP07-9-12-07

Sterile Neutrinos – Physics beyond the Standard Model

  • Fourth (fifth) mass state with high mass splitting triggered by LSND

appearance of from beam at short base line ~30m!

  • Implies m2 ~ 1eV2
  • Also motivated from cosmology

Sorel et. al., Phys.Rev.D70:073004,2004.

e

  • μ
  • (3+1)

(3+2)

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SLIDE 22

Raghavan—TAUP07-9-12-07

LENS Sterile Cr source inside LENS

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SLIDE 23

Raghavan—TAUP07-9-12-07

Active - Sterile Neutrino Oscillations in LENS

Survival probability of e:

51 2 2 5 2 5 41 2 2 4 2 4

sin ) 1 ( 4 sin ) 1 ( 4 1 x U U x U U P

e e e e ee

  • Cross terms such as are neglected
  • 2

5 2 4 e e U

U ) ( / ) ( ) ( 27 . 1

2 2

MeV E m L eV m x

ij ij

  • =

Active – sterile mass splittings and mixing parameters compatible with LSND and the null SBL data ( from Sorel et al., Phys. Rev.D70:073004,2004 )

With m2 ~ 1 eV2 and E ~ 0.753 MeV (from 51Cr), full flavor recovery occurs in ~2m, directly observable in a lab-scale detector. Design options for LENS

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SLIDE 24

Raghavan—TAUP07-9-12-07

Statistical precision of oscillation parameter measurement in LENS

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SLIDE 25

Raghavan—TAUP07-9-12-07

Active – Sterile Oscillation Sensitivity with LENS

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SLIDE 26

Raghavan—TAUP07-9-12-07

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SLIDE 27

Raghavan—TAUP07-9-12-07

Solar Nu’s –Contd:

Model independent fluxes Borexino & LENS Borexino Signal (CC + NC) e+ x LENS Signal (CC) ) e only Possibility of obtaining solar neutrino

Fluxes independent of Solar models

7Be

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SLIDE 28

Raghavan—TAUP07-9-12-07

5”PMT Passive Shield

Mirror

5”PMT Passive Shield

Mirror

Opt segmentation cage

InLS

500 mm

InLS

LS Envelope 500 mm

MINILENS

Final Test detector for LENS

Goals for MINILENS

  • Test detector technology

Medium Scale InLS production Design and construction

  • Test background suppression of In

radiations by 10-11 Expect ~ 5 kHz In -decay singles rate; adequate to test trigger design, DAQ, and background suppression schemes

  • Demonstrate In solar signal

detection in the presence of high background (via “proxy”) Direct blue print for full scale LENS

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SLIDE 29

Raghavan—TAUP07-9-12-07

Proxy pp nu events in MINILENS from cosmogenic

115In(p,n)115Sn isomers

  • Pretagged via μ, p tracks
  • Post tagged via n and

230 μ 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

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SLIDE 30

Raghavan—TAUP07-9-12-07

The Kimballton Underground Facility Depth 1400 mwe

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SLIDE 31

Raghavan—TAUP07-9-12-07

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SLIDE 32

Raghavan—TAUP07-9-12-07

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SLIDE 33

Raghavan—TAUP07-9-12-07

Russia:

INR (Moscow): I. Barabanov, L. Bezrukov, V. Gurentsov,

  • V. Kornoukhov, E. Yanovich;
  • U. S.:

BNL:

  • R. L. Hahn, M. Yeh;

Indiana U. Rex Tayloe

  • U. North Carolina:
  • A. Champagne;

North Carolina State: Albert Young Louisiana State: J. Blackmon, C. Rascoe, Q. Zeng; Princeton U. : J. Benziger; South Carolina State: Z. Chang, Virginia Tech:

  • C. Grieb, M. Pitt,

R.S. Raghavan, D. Rountree, R.B. Vogelaar;

LENS Collaboration (Russia-US: 2007)