# Presentation: 869866

## Kevin T. Lesko
Institute of Nuclear and Particle Astrophysics
for the SNO Collaboration
June 18, 2001

**Institute of Nuclear and Particle Astrophysics**
***for the SNO Collaboration***
**June 18, 2001**

- First Physics Results from the
- Sudbury Neutrino Observatory

## Sudbury Neutrino Observatory

**Sudbury Neutrino Observatory**

- Introduction & Summary
-  Detector Response & Data Analysis
-  Results & Implications
-  Outlook for SNO & other Experiments

## The Solar Neutrino Problem

**“...****to see into the interior of a star and thus verify directly the hypothesis of nuclear energy generation in stars.”**
**Phys. Rev. Lett. 12, 300 (1964); Phys. Rev. Lett. 12, 303 (1964)**** **
***	******Bahcall and Davis***

## The Solar Neutrino Problem

- Subsequent 35 years have seen five experiments all measure a deficiency of solar neutrinos

- Either
- Solar Models are Incomplete or Incorrect
- Or
**Neutrinos Undergo Flavor Changing Oscillations**

## The Sudbury Neutrino Observatory

- 17.8 m Diameter Support Structure for 9456 PMTs, 56% coverage

- 1006 Metric Tons D2O

- 12.01 m Diameter Acrylic Vessel

- 1700 Metric Tons  Inner
- Shielding H2O

- 5300 Tons Outer
- Shield H2O

- Urylon Liner and
- Radon Seal

- Ultra-low Activity
- Components

- Clean Room Construction

- Ultra-Pure Water

- NIM A449, 127 (2000)

## SNO

- “Lowest Background” Laboratory On Earth

**SNO**

## Physics Program for SNO

**Physics Program for SNO**

- Charged Current
- 	e+de-+p+p
- 	Ethresh=1.4 MeV
- Elastic Scattering
- 	x+e-x+e-
- Neutral Current x+dx+n+p
- 	Ethresh=2.2 MeV

-    D2O + NaCl
- CC, ES, enhanced NC 	(~8.6 MeV, n ~ 86% ~45% above threshold)

-     D2O + NCDs (3He Prop. Counters)
- Concurrent CC & NC, ES (n ~ 45%)

- Pure D2O
- CC, ES, reduced NC** **
- (6.25  MeV, n ~ 24%)

- π

## Physics Program for SNO

- Energy

## SNO’s Major Signals

**Spectra distortions to ES and CC**

## SNO’s Major Signals

## SNO’s Major Signals

- Elastic Scattering
- also *measures* other
- Neutrino Flavors

## Evidence for Solar Neutrino Oscillations

## Calibration, Detector Response and Data Analysis

**Optical Calibration**
**Energy Response**
**Event Reconstruction**
**Position resolution**
**Angular resolution**
**Energy resolution**
**Detector Response**
**Monte Carlo Simulations**

**Livetime**
**D****2****O Isotopic Purity**
**Instrumental Backgrounds**
**Low Energy Physics Backgrounds**
**D****2****O**
**Acrylic Vessel**
**H****2****O & PMT**
**High Energy ******** rays**

- Do Everything at least two ways

## Calibration Systems

- Calibration Systems

## Event Reconstruction

- Calibrated with:
- 	16N ’s and 8Li ’s throughout D2O
- 	16N ’s in H2O

- 8Li Reconstruction

- Z-axis Scan with 16N

- Vertex resolution =16 cm

## SNO’s Energy Response at the Center of the Detector

- 6.13 MeV 
- ~14 MeV 
- 19.8 MeV 

- 1% E/E ~ 3% /

## Energy Response to Neutrons throughout the Detector

- 6.25 MeV capture 

- SNO Preliminary

## SNO’s Monte Carlo Model

**Photon Generation, Transport and Detection**
**Detector Geometry, Status and Conditions**

- x 10,000** **

## Instrumental Background Removal

- Acceptance
-  measured with 16N and 8Li sources
-  0.9962 +0.0073/-0.0063

- Residual Contamination
-  bifurcated analysis + handscanning
-  < 0.2%

## D2O Backgrounds

- Measured both by Radioassay and Cerenkov light at
- ~10-15 g/g!

- Target Levels would produce 1 neutron/day or 10% SSM

## Acrylic Vessel Backgrounds

-  “Berkeley Blob”

- Activities assayed are _x0008_	<10% Targets ~0.2 ppt
- Or  ~ 6 g Th or U
- Original Target was
- 	60 g Th or U

- y (cm)

- x (cm)

## Radioassay and in situ Cerenkov Measurements

- Radioassay and *in situ* Cerenkov Measurements

**H****2****O and PMT Backgrounds**

## Signal Extraction

**“****Background Free” Analysis **
**	****R < 550cm, T > 6.75 MeV**
**	****Lower Systematic Errors**
**	****Fit CC, ES, Neutrons PDFs**
**	****Functions (R****3****, cos********sun****, T)**
**	****Extended Maximum Likelihood**

**Signal Extraction**

**Consistent Results**

**Variable Fiducial Volume (6.5 m) and Energy Thresholds **
**	****Fit CC, ES, Neutrons, Bckgrds PDFs**
**	****Functions (R****3****, cos********sun****, T)**
**	****Extended Maximum Likelihood**

## Signal Extraction Results

- Data resolved into CC, ES, neutron components with Monte Carlo pdfs of Teff, cossun, (R/RAV)3 With the hypothesis of no neutrino oscillations
- 	CC			975.4 ± 39.7 events
- 	ES			106.1 ± 15.2 events
- Tail of Neutrons		87.5  ± 24.7 events

- 240.9 live-days
- between 11/99-1/01

- No statistically significant differences between Blind and Open data sets (75 days/166 days)

## Results

**Radial**
**Distribution**
**of Neutrinos**

## Results

- Direction of Events with respect to the SUN

**Results**

- 6.75 MeV threshold

## Results

**CC spectrum normalized to predicted ****8****B ** **spectrum.**** **
****** ****no evidence for shape distortion.**

- Charged Current Energy Spectrum

**Results**

## Systematic Uncertainties

- N(HE   events): <10 events (68% CL)

## CC is low compared to ES

**CC** is low compared to **ES**

*(Fluxes in 10**6**/cm**2**/s)*

## CC and ES Results

## CC and ES Results

## SNO + Super-K Results

- Flavor Changing Appearance!

- These data are evidence with >99.96% confidence that e produced in the sun are transformed into  and or  by neutrino oscillations

********

## Solar Flux Results

- (e) = 5.44 ± 0.99 x 106 cm-2s-1

- (e) = 5.05 +1.01/-0.81 x 106 cm-2s-1
-  Standard Models

- ( ) = 3.69 ± 1.13 x 106 cm-2s-1

## SNO + Super-K

- “Just-So2” (m2 = 6  10-12 eV2 ) excluded 3.3 
- “SMA sterile” excluded to a similar level of confidence
- “Vacuum Sterile” requires more effort:
- 	If oscillation with maximal mixing to a sterile neutrino is occurring the SNO CC-derived 8B flux above a threshold of 6.75 MeV will be essentially identical with the integrated Super-Kamiokande ES-derived 8B flux above a threshold of 8.5 MeV .
- 	 Correcting the ES threshold the flux difference yields a flux difference of 0.53 ± 0.17 or
- 	3.1  exclusion of maximal mixing to sterile neutrinos

## SNO + Ga + Cl + SuperK

- To Active Neutrinos

- To Sterile Neutrinos

## SNO’s Immediate Future

**Conductivity Measurements Taken During Salt Addition**

**Salt Injected**
**28 May 2001**

## SNO’s Immediate Analysis Future

**Lower analysis threshold for NC and Shape Analysis from pure D****2****O data**

**Don’t touch that dial...**

**Calibration of D****2****O + NaCl data**

**Seasonal and other Exotica**

**hep-neutrino analysis**

**Day/Night analysis**

**Muons**

## The Bigger Picture

- 1) What is the absolute  mass scale?
- 2) Determine solar oscillation parameters:  SNO, KamLAND, Borexino
- 3) What are the mixing parameters, especially 13?
- 4) Is the neutrino its own antiparticle?
- 5) What is the nature of CP violation in the neutrino sector?
- 6) Extended Standard Model to embrace neutrino mass

- H. Murayama

## Implications for Cosmology

- M(e) < 2.8 eV (Bonn *et al*. - Mainz)
- m (atmospheric ) ~ 50 meV (Toshito *et al*. Super-K)
- ~10-5 ≤ m (solar ) ≤ ~30 meV (SNO + Apollonio *et al.)*

- 0.001 ≤  ≤ 0.18

- .05 ≤  ≤ 8.4ev

## SNO Collaboration

- J. Boger, R. L Hahn, J.K. Rowley, M. Yeh
**Brookhaven National Laboratory**
-  I. Blevis, F. Dalnoki-Veress, W. Davidson, J. Farine, D.R. Grant, C. K. Hargrove, I. Levine, K. McFarlane, C. Mifflin, T. Noble, V.M. Novikov, M. O'Neill, M. Shatkay, D. Sinclair, N. Starinsky
**Carleton University**
- J. Bigu, J.H.M. Cowan, E. D. Hallman, R.U. Haq, J. Hewett, J.G. Hykawy, G. Jonkmans, A. Roberge, E. Saettler, M.H. Schwendener, H. Seifert, R. Tafirout, C. J. Virtue.
**Laurentian University**
- Y. D. Chan, X. Chen, M. C. P. Isaac, K. T. Lesko, A. D. Marino, E. B. Norman, C. E. Okada, A. W. P. Poon, A. R. Smith, A. Schülke, R. G. Stokstad.
**Lawrence Berkeley National Laboratory**
- T. J. Bowles, S. J. Brice, M. Dragowsky, M.M. Fowler, A. Goldschmidt, A. Hamer, A. Hime, K. Kirch, G.G. Miller, J.B. Wilhelmy, J.M. Wouters.
**Los Alamos National Laboratory**
- E. Bonvin, M.G. Boulay, M. Chen, F.A. Duncan, E.D. Earle, H.C. Evans, G.T. Ewan, R.J. Ford, A.L. Hallin, P.J. Harvey, J.D. Hepburn, C. Jillings, H.W. Lee, J.R. Leslie, H.B. Mak, A.B. McDonald, W. McLatchie, B. Moffat, B.C. Robertson, P. Skensved, B. Sur.
**Queen's University**

- S. Gil, J. Heise, R. Helmer, R.J. Komar, T. Kutter, C.W. Nally, H.S. Ng,Y. Tserkovnyak, C.E. Waltham.
**University of British Columbia**
- T.C. Andersen, M.C. Chon, P. Jagam, J. Law, I.T. Lawson, R. W. Ollerhead, J. J. Simpson, N. Tagg, J.X. Wang
**University of Guelph**
- J.C. Barton, S.Biller, R. Black, R. Boardman, M. Bowler, J. Cameron, B. Cleveland, X. Dai, G. Doucas, J. Dunmore, H. Fergani, A.P. Ferraris, K.Frame, H. Heron, C. Howard, N.A. Jelley, A.B. Knox, M. Lay, W. Locke, J. Lyon, S. Majerus, N. McCaulay, G. McGregor, M. Moorhead, M. Omori, N.W. Tanner, R. Taplin, M. Thorman, P. Thornewell. P.T. Trent, D.L.Wark, N. West, J. Wilson
**University of Oxford**
- E. W. Beier, D. F. Cowen, E. D. Frank, W. Frati, W.J. Heintzelman, P.T. Keener, J. R. Klein, C.C.M. Kyba, D. S. McDonald, M.S.Neubauer, F.M. Newcomer, S. Oser, V. Rusu, R. Van Berg,  R.G. Van de Water, P. Wittich.
**University of Pennsylvania**
- Q.R. Ahmad, M.C. Browne, T.V. Bullard, P.J. Doe, C.A. Duba, S.R. Elliott, R. Fardon, J.V. Germani, A.A. Hamian, R. Hazama, K.M. Heeger, M. Howe, R. Meijer Drees, J.L. Orrell, R.G.H. Robertson, K. Schaffer, M.W.E. Smith, T.D. Steiger, J.F. Wilkerson.
**University of Washington**
- R.G. Allen, G. Buhler,** ****H.H. Chen***
**University of California**, **Irvine**
-  * Deceased

## Thanks to: INPA, NSD, CSEE, NERSC, DoE 

**Thanks to**: INPA, NSD, CSEE, NERSC, DoE
- _Installation_: Milt Moebus, Steve Turner, Joe Gonzalez
- _Mechanical Engineering_: Peter Purgalis, Gary Koehler, Yoichi Kajiyama, Dave Beck, Milt Moebus, Bob Fulton

## For Details, Preprint, Links, Pictures, and Releases and References:

**SNOHP1.LBL.GOV**
**or**
**www.sno.phy.queensu.ca**
**at LANL xxx**** Nucl-ex/0106015**

## Slide 43

## Muons in SNO

## Slide 45