active-sterile neutrino oscillations in lens c. grieb, j. link and r. s. raghavan virginia tech
DESCRIPTION
Active-Sterile Neutrino Oscillations in LENS C. Grieb, J. Link and R. S. Raghavan Virginia Tech XII Neutrino Telescopes Venice, March 8 2007. LENS is a high-resolution, real time spectrometer for low energy solar neutrinos such as pp, Be etc Why LENS for active-sterile oscillations? - PowerPoint PPT PresentationTRANSCRIPT
Active-Sterile Neutrino Oscillations in LENS
C. Grieb, J. Link and R. S. RaghavanVirginia Tech
XII Neutrino TelescopesVenice, March 8 2007
LENS is a high-resolution, real time spectrometer for low energy solar neutrinos such as pp, Be etc
Why LENS for active-sterile oscillations?
•Novel Technology brings unique tools in play for short baseline disappearance experiments using monoenergetic e-flavor neutrinos from a radioactive source
•Parasitic measurement to solar neutrino program—sterile neutrinos are free!
•Sensitivity highest, well beyond Miniboone projected - new physics and astrophysics irrespective of LSND and Miniboone result
Two part Talk
I LENS overview- Properties relevant to short baseline oscillations
II How to make a sensitive search for active-sterile oscillations in LENS ?
Russia INR (Moscow): I. Barabanov, L. Bezrukov, V. Gurentsov,
V. Kornoukhov, E. YanovichIPC (Moscow): N. Danilov, G. Kostikova, Y. Krylov INR (Troitsk) I: J. Abdurashitov, V. Gavrin. et al. II: V. Betukhov, A. Kopylov, I. Oriachov, E.Solomontin
U. S.:BNL: R. L. Hahn, M. YehUNC: A. ChampagneORNL: J. Blackmon, C. Rasco, Qinlin Zeng, A. Galindo- UribarriPrinceton U. : J. BenzigerSCSU: Z. ChangVirginia Tech: C. Grieb, J. Link, M. Pitt, R.S. Raghavan, R. B. Vogelaar,
LENS-Sol / LENS-Cal Collaboration(Russia-US: 2004-)
115In ( 95.7%) = 6.4x1014 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 s
max = 498.8
= 16 ps
= 231s
9/2+
1/2+
3/2+
7/2+
11/2-
0
497.3
612.8
713.6
7/2+ 1857
B(GT) ~0.01; Q =1362
e
115In ( 95.7%) = 6.4x1014 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 s
max = 498.8
= 16 ps
= 231s
9/2+
1/2+
3/2+
7/2+
11/2-
0
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%) = 6.4x1014 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 s
max = 498.8
= 16 ps
= 231s
9/2+
1/2+
3/2+
7/2+
11/2-
0
497.3
612.8
713.6
7/2+ 1857
B(GT) ~0.01; Q =1362
e
115In ( 95.7%) = 6.4x1014 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 s
max = 498.8
= 16 ps
= 231s
9/2+
1/2+
3/2+
7/2+
11/2-
0
497.3
612.8
713.6
7/2+ 1857
B(GT) ~0.01; Q =1362
e
The Indium Low Energy Neutrino Tag
SnSneIne115*115115 2
Tagged ν –capture reaction in IndiumLENS is the only developed CC real time detector for solar neutrinos
Unique:• Specifies ν Energy
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
signalDownside:• Bgd from 115In radioactivity to ( pp nu’s only) rate= 1011 x
signalTools:1. Time & Space coinc.
Granularity (106suppression)2. Energy Resolution In betas <500 keV; ∑Tag =
613 keV3. Other analysis cuts
signal delay Tag cascade
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
Status
Design of Detector Cubic Lattice Chamber
Composition InLS
PC based: In contentLight attenutation L(1/e)
Signal Eff Pe/MeV NEW : LAB based- Similar as in PC
>8% >10m900
Indium Mass(1900 pp/5y) 10 ton
Total Mass 125 ton
PMT’s 13,300
Neutrino detection eff. 64% (pp)>85% all other
S/N (β+γ (All In decay modes) ~3 (pp)>> 3 (ALL OTHER)
Major Progress --LENS < Towards Hi Precision pp >• Hi Quality InLS Developed• Background Analysis Insights• New Detector Design Invented
UV/Vis absorbance of zVt45 (pH 6.88) with time
-0.01
0
0.01
0.02
0.03
0.04
0.05
350 390 430 470 510 550 590 630 670l (nm)
Nor
mal
ized
Abs
orb
ance
10/06/05
01/23/06
03/22/06
05/31/06
8.6 m after 8 months
Transparency of InLS
Indium --Background Structure – Space / Time coincidence
Signal
E() -114 keV
116 keV
497 keV
115In
115Sn
e/
=4.76s
Background:
Random time and space coincidencebetween 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 bylow energy (e-/) ( )and Compton-scattered ( )->time/space coincidence-> tag fixed energy 613keV->compton scattered shower
115In
β0 + n (BS) (Emax = 499 keV)
498 keV
*Cattadori et al: 2003
β1 (Emax< 2 keV)(b = 1.2x10-6)*
115Sn
Signal and Indium-Background Ratespp Signal
/y /t In
Bgd tot
/y /t In
Bgd A1
/y /t In
Bgd A2
/y /t In
Bgd B
/y /t In
Bgd C
/y /t In
RAW 62.5 79 x 1011
Valid tag (Energy, Branching, Shower) in Space/Time delayed coinc. with prompt event in vertex
55 2.76 x 105 8.3 x 104 2.8 x 103 1.9 x 105 43.9
+ ≥3 Hits in tag shower 49.5 6.23 x 104 5.81 x 104 2.76 x 103 1.4 x 103 43.7
+Tag Energy = 613 keV 44.4 458 0.48 5.2 445 8.0
+Shower Radius 43.9 270 0.48 5.1 264 0.73
+Hit Separation 40.2 13.3 ±0.6 0.48 4.7 8.1 0.004
Signal / Background ~3 with pp- event detection efficiency 64%Remember: only pp- events affected by Indium Background, 7Be, pep and CNO Background-free
Technology
Indium Liquid Scintillator Chemistry RobustLENS-Grade Properties Demonstrated in Lab ScaleLarge Scale Production Next
Detector DesignNovel Scintillation Lattice InventedOptical properties simulated and analyzed for optimal DesignPrototypes in development
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 Stability: at least 1 year5. InLS Chemistry - Robust
Basic Bell Labs Patent,Chandross & RSR. 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 670l (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 Status
Milestones unprecedented in metal LS technology
LS technique relevant to many other applications
Sample pH In% S%Abs@430nm at different time
Begin 1 Mon 3 Mon 5 Mon 8 Mon 9 Mon
zVt39 7.24 8.7 64 0.001 0.002 0.003 0.009 0.012 0.013
zVt40 7.22 8.4 63 0.001 0.003 0.005 0.006 0.010 --
zVt41 7.09 8.4 59 0.003 -- -- 0.008 0.009 --
zVt46 6.98 8.5 58 0.002 -- -- 0.007 0.008 --
zVt38 6.94 8.3 61 0.002 0.003 0.005 0.005 0.006 0.007
zVt47 6.92 8.0 59 0.0025 -- 0.005 -- 0.006 --
zVt45 6.88 8.2 56 0.003 0.004 0.005 0.005 0.005 --
zVt44 6.86 8.6 56 0.003 0.004 0.004 0.004 0.005 --
Long Term Stability of L1/e of InLS
The S values of the samples were found not to change with time. The L1/e of the samples synthesized at pH 6.88 were found to stabilize
in 3 months, and their L1/e have stayed > 8 m for 8 months.
Optimum value for the extraction pH ~6.88
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 ReflectionA small part of light crossing
a gap is reflected back and undergoes multiple reflections, thus, suffers extra bulk absorption in the liquid
Upper limit ~1700pe/MeV (L=10m) - reach via antireflective coating on films?
Adopt1020 pe/MeV7.5 cm cells
Photoelectron yield versus number of cells:
4x4x4m CubeAbsorption length = 10m
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
Real life issue--Foil Surface Roughness andImpact on the Hit Definition
Can we get away with a single foil optical structure-? “Hard Lattice”
No trapped air
Easier construction
More robust
Most photons still “channeled” crit~60
Still Good event localization
Less trapping
Greater light output
Solid Teflon Segmentation
Challenges:
How to deal with “spray”?
Background rate
Trigger logic
5” PMTPassiveShield Mirror 5” PMTPassiveShield Mirror
Opt segmentation cage
InLS500 mm
InLS
LS Envelope
500 mm
MINILENSFinal Test detectorfor 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
Source DecayMode /Produced by
EkeV) Ee=
E0.114 keV
Background
37Ar Haxton
EC/ (n, 50.5 d 814(100%) 700 Int. Bremms. 0-814;~5x10-4 h/decay
51Cr RSRKuzmin
EC/ (n,) 40.1 d 751 (90%) 637 320 (10%) Imp. ’s (MeV) %??
65Zn Louis Alvarez
EC(+)/ (n,) 353 d 1350 (50%) 1236 1115 511 (2%); Imp. ’s.
Table I: Characteristics of neutrino Sources for LENS-CAL
Neutrino Energy typically 700 keV
•Sterile neutrino tests in LENS•Unique advantages
•Put strong articial Neutrino Source into LENS•Pure, e-flavor, monochromatic neutrino line•Measure Pee as function of Distance—Disappearance Measurement•3-D location allows measurement of RADIAL dependence of Pee•All systematic, normalization and spectral peeling errors endemic in broad beam reactor spectra drop out•Measure Pee (r) with100,000 detectors, not just 2 or 3
Already planned: LENS CalMCi Cr Source in LENSCalibrate In X-section
Parasitic measurementFor sterile neutrinos
Active Sterile Osc of mono-Chromatic 753 keVpure e-flavored neutrinos
ViaSpatial distribution ofFlavor Survival in ~5 m
Active-Sterile Oscillations
LENS OFFERSUNIQUE TESTFor Sterile Neutrinos
Sterile Neutrinos—( Neutrinos of the wrong helicity)Physics well beyond the Standard Model
--Fourth (Fifh) mass state with high mass splitting triggered by LSND
Appearance of e flavor from μ beams at short base lines ~30m!Implies Δm2 ~ 1 eV2
Pee = 1 − s2 (e4) s2 (41) – s2 (e5) s2( 51)
where cross terms such as s2 (e4)s2 (e5) are neglected. In (2) the mixing terms
s2( en) = sin2 2θen = [4U2 (en) (1-U2(en)]
and the frequencies s2 n1 = sin2 [(1.27Δm(n1)2 eV2 ) x L(m)/Eν(MeV)). The values of s(en) and Δm2 are from
Ref 4 (Table 1). With Δm2 = 1 eV2 and Eν ~0.753
MeV (from 51Cr), (2) full flavor recovery occurs in ~2m, directly observable in a lab-scale detector
Statistical precision of oscillation parameter measurement in LENS
Gail Maclaughlin (Private Comm.)
Conclusions
•LENS offers a new and sensitive tool for searching for active-sterile nu oscillations
•The advanced sensitivity allows the search in its own right towards new physics and astrophysics
•Independent of LSND or Miniboone results
•Parasitic measurement—No extra resources needed