# Presentation: 733778

## Neutrino Luminosity of the Sun 

***Measuring the ***
***Neutrino Luminosity of the Sun****** ***
**PANIC05 Neutrino Satellite Meeting**
**October 29, 2005**
**Christian Grieb**
**Virginia Tech**

## LENS-Sol / LENS-Cal Collaboration

- 					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. Rascoe, A. Galindo-Urribari;
**	****	****	****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-)**

## LENS-Indium: SCIENCE GOAL

** ****Measure the low energy solar ******** spectrum (pp, ****7****Be, CNO)**
** ****± ****~3% pp- ******** flux**
** ****Experimental tool: Tagged CC Neutrino Capture in Indium**
***    ***
***LENS-Cal:***
** ****Measure *****precise***** B(GT) of ****115****In CC reaction using **
**      ****MCi ****51****Cr neutrino source at BAKSAN**
** ****Tagged ****ν****-capture  to *****specific *****level of  ****115****Sn**
** *****Note:***** B(GT) = 0.17 measured via (p,n) reactions**

**LENS-Indium: SCIENCE GOAL**

**Precision Measurement of the Neutrino Luminosity of the Sun**

## LENS-Indium: Foundations

**Threshold:** 114 keV  pp-’s
**115****In abundance:** ~ 96%
**Background Challenge:**
-  Indium-target is radioactive!
-    ( = 6x1014 y)
-  115In β-spectrum overlaps pp- signal
**Basic background discriminator:**
-   Tag energy: E-tag = Eβmax +116 keV
** **
***7******Be, CNO & LENS-Cal signals***
***not affected by Indium-Bgd!***

**LENS-Indium: Foundations**

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

## Expected Result: 

**pp**

**7****Be**

**pep**

**CNO**

**Detector Resolution 800 pe / MeV**

**S/N=1**

**S/N=3**

**Random coinc. Bgd**

** ****Signal (********= 4.76 μs)**

**LENS-Sol Signal**
** ****=**** **
** ****SSM(low CNO) + LMA**
**x**
**Detection Efficiency ******
** ****pp:****   ****** = **64%**
** ****7****Be:****  ******** = 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 Neutrino Spectrum**

**Signal extracted  from fit of coinc. time spectrum**
** ****to isomeric exp. decay ****+ Random Coinc. Bgd**

**Access to pp spectral *****Shape****** *****for the first time**

**Delay time**

**Signal Electron Energy (MeV)**

## 	so far LMA only from Kamland    , is this true

- 	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     ?
-  **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 LENS**
**APS Nu Study 2004******** ****Low Energy Solar Nu Spectrum: one of 3 Priorities**

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

**Low Energy Neutrinos:**
**Only way to answer these questions !**

## NEW SCIENCE - Discovery Potential of LENS

-    Measured Neutrino Luminosity (~4%)
- Photon Luminosity ↔ Neutrino Luminosity
- Ultimate test of the neutrino & the sun
- Experimental status - No useful constraint!
- Test solar model and neutrino oscillations with one measurement
-  Astrophysics:   L > Lh  Is the sun getting hotter?
-  		  L < Lh   Cooling or a sub-dominant non-nuclear
-                                           source of energy in the sun?
-  Precision values of θ12, θ13; Sterile Neutrinos?

**NEW SCIENCE - Discovery Potential of LENS**

**In 5 years (with ********- source calibration):**

## Status Fall 2003                               Status Fall 2005

**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 190t
- In: 10t-15t for 1970 pp ’s /5y
- PMTs: 13,300 (3”) - 6,500 ( 5”)
- pp- Detection Efficiency: 64-45%
- S/N ~3  (ALL In 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/MeV
- Total mass LS: 6000t
- 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)

## Indium Liquid Scintillator Status

**8% InLS (PC:PBD/MSB)**
**              ****10800  h****ν**** / MeV**

**BC505 Std**
**12000 h********/MeV**

**In 8%-photo**

**Light Yield  from Compton edges**
**of ****137****Cs ********-ray ****Spectra**

- 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

**Basic Bell Labs Patent,**
**filed  2001, awarded 2004**

******  ****(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**

## New  Detector Concept -

**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 double foil
- mirror in liq. @~2bar

**New  Detector Concept -**
**The Scintillation Lattice Chamber**

- Light propagation
- in GEANT4

- Concept

## Foil Surface Roughness and

**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

**Foil Surface Roughness and**
**Impact on the Hit Definition**

## Light loss by Multiple Fresnel Reflection

**Black: L= 10m with foil imperf.**
**Pink****:  L=10m without foil imperf.**
**Blue****:  L=7m with foil imperf.**
**Red****:   L=7m without foil**** imperf.**

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

**Light loss by Multiple Fresnel Reflection**

**4x4x4m Cube**

**Adopt**
**1020 pe/MeV**
**7.5 cm cells**

## Indium Radioactivity Background

**Indium Radioactivity Background**

**BGD**

**E(********) -114 keV (e1)**

**116 keV (g2)**

**498 keV (g3)**

**115****In**

**SIGNAL**

**115****In**

**115****Sn**

**β****0**** + n******** (BS) **
**(E****max**** = 499 keV)**

**498 keV**

***Cattadori et al: 2003**

**β****1**** (E****max****< 2 keV)**
**(b = 1.2x10****-6****)* **

**115****Sn**

**e/******

****

**Multiple ****115****In decays simulate tag candidate in many ways**

## Indium Radioactivity Background

**Indium Radioactivity Background**

**n ****115****In ********–decays in (quasi) prompt coincidence produce a tag:**
**Basic tag candidate: Shower near vertex (****Nhit ≥ 3****) - chance coincident with ****115****In ****β**** in vertex**
**	****Type A:****	****A1  = ****β**** + BS ******** ****(E****tot**** = 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

## Indium Background Simulations and Analysis

-  ~ 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

## Background Suppression - 

** ****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”**

## Typical LENS-Sol Design Figures of Merit –

- 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”) |

## Summary

- Test of all the concepts and the technology developed so far:
-       **MINI-LENS** -  200 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)**

## Additional Slides

## VT-NRL Low Bgd Laboratory @ Kimballton Limestone Mine VA

**30 min by car from Virginia Tech**

## Direct Measurement of the Central Temperature of 

**Direct Measurement of the Central Temperature of **
**the Sun with High pe/MeV in LENS**

**1000 ****7****Be events**
**2000 ****7****Be events**
**3000 ****7****Be events**
**4000 ****7****Be events**
**6000 ****7****Be events**

**~ 1700 pe/MeV**
**δ****E(1****σ****) = ****0.5 keV**

**Expected precision of centroid energy of  ****7****Be Line in LENS *****(******Statistics only******, 2000 events, 1700 pe/MeV)*****: ****δ****E(1****σ****)   ±  0.5 keV *****  *****                                                                 **
**Predicted solar shift ** **(Bahcall 1993))** **δ****E****= + 1.29 keV**