Neutrino Working Group Kevin T. Lesko

1
Neutrino Working GroupKevin T. Lesko

• - q12 Neutrino Mixing
• - Next Generation
• Solar Neutrino Experiments
• - National Underground Scientific Laboratory

2
Where are we with Neutrinos after SNO KamLAND-I?

• Reduced ne MSW space by 7 orders of magnitude
• No dark side ne (tan2qlt1)
• Most likely LMA (confirmed by KamLAND! assuming
  CPT)
• Support of MSW affects
• Massive neutrinos (small Dm2)
• Large mixing angles

3
Neutrino Mixing Parameter q12

• SNO KamLAND
• Now

• SNO KamLAND
• Next year (guess)

4
Flux measurement limited to 7 -10
How can we do better? How much better can we do?
KamLAND II (7Be)
Flux measurement down to 1-3
Low Energy pp Experiment
5
Neutrino Mixing Parameter q12

• Fundamental neutrino parameter, neutrino
  properties
• The angles are large and at least q12 is
  non-maximal
• Is the MNS matrix unitary?
• Input to CP violation experiment analysis
• Synergisms with other fundamental measurements

6
Physics using the sun 7Be and pp neutrinos
Oscillation Parameter q12 7Be - confirm q12 from
SNO with 7 to 10 pp yields factor 2-3
improvement in q12 1 to 3 unitarity of the MNS
mixing matrix mixing angles are large but not
maximal-why? input into ultimate CP studies
Sterile Neutrinos currently SNO yields 30
limit solar neutrinos absolute intensity good
1 Magnetic Moments looking down to 50 keV
10-11 mB ds/dy Solar Physics SSM - pp flux,
7Be flux CNO - 1.2 to 1.7 MeV, 50
uncertainty FCNO0.1 to 0.2 x 7Be and 20x 8B
Surprises to Conventional Wisdom
7
7Be upgrade to KamLAND
Upgrade a coincidence experiment to a singles,
low energy experiment Backgrounds will be a
dominate concern.

• Dominant backgrounds
• 85Kr
• 210Pb
• 210Bi (from Rn)

8
Backgrounds Spallation, Long-lived radioactivity
Adding solar n signals
7Be window
9
Top of the chains look encouraging, But radon is
leaking in, lots of Kr
7Be
10
7Be Neutrino Experiment at KamLAND
U, Th chains look pretty good, wrt supported
chains Radon and 85Kr require 1106
reduction 210Pb needs large reduction in the
bulk liquid Scintillator Collaboration (US and
Japanese) now gearing up to address these issues.
Japan has received some funding already (site
improvements and some purification upgrades). US
proposal for a KamLAND upgrade is now being
considered by the US collaboration. Proposal
might include items such as improved purification
techniques, fixing lots of piping leaks, fresh
air ducting, cave linings, etc.
11
Next Generation Solar Neutrino Experiment pp n

• Long Term RD Investment
• Not a quick dirty experiment
• RD applicable to several experimental fronts
• Low energy solar neutrino experiments
• Double beta decay
• Other experiments
• Experiments are challenging
• For ultimate physics requires both CC and NC
  measurements
• Requires NUSEL a deep site

12
Issues for Low Energy Solar Neutrino
Experiment Backgrounds Internal External
Detector Performance Detector
Efficiency Detector Resolution Robust
Signal Stability Environmental
Considerations Count Rate
13

• Neutrino Elastic Scattering
• ne,m,t e - gt ne,m,t e

Measure RATE RECOIL SPECTRA of pp ( 7Be,
CNO) 50 keV Threshold ne nm,t Cross
Sections Accurately Known. High Statistics for
Moderate Detector Mass ( gt 90 of
f(solar) 3000 6000 events per 10 tonne-yr )

• f(pp) Theoretical Prediction (SSM) 1
• (more precisely predicted than reactors 2 Bugey
  potential Standard Candle)
• Not affected by power companies or Atomic Energy
  Commission reporting of Power Levels

14
Preliminary Design of a Low Energy Solar Neutrino
Detector
Space Infrastructure Construction Safety
Kajiyama Lanou Lesko Poon Seidel LBNL Brown U.
15
Low Energy Solar Neutrino Experiment LDRD

• Why Superfluid Helium?
• High Rate ES ( 2 events/tonne/day detected)
• Intrinsically pure
• Potentially good signal/bckgrd discrimination
• Significant RD invested already
• scintillation yields, Rayleigh scattering,
  redundant signals, signal processing, background
  discrimination, etc.

• Why Berkeley Lab?
• Backgrounds (shielding induced), Calibration
  and Calculations
• Detector Development, signal processing
  (scintillation light)
• Detector Design Construction
• Connections to UCB Physics
• History with Neutrinos
• Excellent Connection to LRP NUSL

Plan Backgrounds Develop Detection
Techniques Develop Prototype
16
Participation of Berkeley Lab in NUSEL

• Science Driven
• Positions Berkeley Lab with LRP priority
• Major Roles in New Laboratory
• Science Experiments
• Low Energy Solar Neutrino Experiment RD
• Monte Carlo Simulations Backgrounds
• Detector RD
• Prototype Detectors
• Ultralow Background Counting Facility
• Monte Carlo Simulations
• Detector Designs
• Engineering Design and Conceptual Design
• Earth Sciences Division
• Nuclear Astrophysics - under discussion
• Double Beta Decay - under active discussion

17
Why should LBL Participate in NUSEL?

• Connections to existing experiments, upgrades,
  and future experiments.
• SNO
• KamLAND
• Astrophysics
• Double Beta Decay
• Cuore Majorana
• Low Background Counting
• Engineering, Design, Management
• Major Priority for Nuclear Physics Community
• Long baseline experiments, CP violation, proton
  decay in the future.

18
What is the status of NUSEL? What is Berkeleys
role in NUSEL?

• Workshops 2000-2002
• Long Range Planning Process
• (NSAC, SNOWMASS)
• National Priority
• NSF Proposal submitted
• Panel and Paper Reviews
• NeSS Workshop
• Awaiting NSF Board Action
• NSF Proposal being refined
• Defining LBL Role in Proposal

• Still no action from NSF
• Homestake not flooded
• Proposal being refined and improved
• NSF Management urges patience
• RecentlyOSTP discussing Major Initiative in
  Particle/Astrophysics highlighting NUSEL

Lesko NUSEL Executive Committee Poon, Heeger
members of working groups
19
NUSEL - recent news
Barrick just (10 April) announced plans to
flood the Homestake mine beginning on 14 April.
A major set back for Homestake proposal from the
University of Washington. - Could just be
posturing by Barrick to obtain operating expenses
or attention. - If real it would open the door
to consideration of the full range of siting
options San Jacinto, Nevada, Henderson mine,
Eastern California, etc. OSTP considering a
major initiative in Astro-particle physics, NUSEL
is a major focus of this initiative.
20
q12 Low Energy Solar Neutrino Expt National
Underground Laboratory
Summary
Multiple excellent science objectives Long
term mission Synergism with other fields and n
physics Capitalizes on lab expertise and
experience Positions lab with community
priorities
21
(No Transcript)
22
Status of HERON

• Substantial RD already done with prototypes
• Absolute measure of scintillation yield
  gt30,000 photons/MeV Rayleigh scattering
• Demonstrated two-channel detection of low
  energy bs as photons phonons
• Developed calorimeter wafers magnetic readout.
  6 eV FWHM on 6 keV x-ray
• Full simulation of coded aperture on backgnd
  signal photons.
• current version 3x10-3 backgnd
  reject almost good enough for no electroforming

• In progress
• New prototype expts. on scintillation
  drifted charge ( e-bubbles).
• Experiments for single 16eV photon
  sensitivity on larger calorimeters.
• Testing different versions of coded aperture
  in full simulation.
• Decision on constructing sizeable prototype
  (1-1.5 yr.?)

• When could there be a full HERON?
• a) When where will there be an
  underground lab?
• b) Fabricate construct underground.
• c) Infrastructure for doing so?
• d) 2-3 yrs. From a) c).
• e) Cost 30-40 M (FY2001 )
  detector, shields aux. equip.

23
Low Energy Neutrino Experiment Challenges

• Requires VERY LOW THRESHOLD
• lt 50 keV
• FORMIDABLE BACKGROUNDS
• target, container, environment, muon spallation
• SIGNAL SINGLE ELECTRON RECOIL
• NEEDS PRECISION
• high statistics, need to pin systematics on FV,
  dE/E, etc.
• s(nm,t)/s(ne) 1/6
• appearance but lower sensitivity to NC
• COMPLEMENTARY CC EXPTS VERY LARGE
• low event rate/ton cross-sections less
  well known

24
How does HERON address these challenges?

• A cryogenic scintillation-plus detector.
• Use Superfluid helium as target superfluid free
  of any other substance
• Helium is strong scintillator at 16 eV. gt30,000
  photons/MeV l(Rayleigh) gt 200 m
• Redundant detection channels. Scintillation,
  Phonons e-bubble.
• No PMTs. Scintillation, phonons, electron all
  detected on same sapphire wafer calorimeters,
  looking into additional detection devices
• Depth gt4500 mwe and immunity of Helium to muon
  spallation/ capture
• External shield from hall rock activity,
• BUT Helium not good self-shield from any
  activity in container
• Capitalize on different
  signature of background. gs ? Multiple Comptons
• Good measurement of event
  positions topology.
• utilize coded aperture
  wafer array point vs. distributed source
• Possible electroforming of
  interior cryostat.

25
Preliminary Design of a Low Energy Solar Neutrino
Detector Superfluid Helium (HERON) type detector
Mass Backgrounds Shielding Construction
Kajiyama Lanou Lesko Poon Seidel
26
Log-Likelihood Coded Aperture
27

• 20 tonnes total Helium.
• Variable fiducial.

28
From Aspen 2002
Log(Dm2)
SNOCl Ga Standard
SNOClGa (5 2 theory)
Log(tan2q)
Log(Dm2)
SNOClGa (12 theory)
Barger 0204253
Log(tan2q)
29
Where will we be in 3-5 years?

• Neutrino Oscillations - fundamental issues
• LMA, Dm2 lt 1 x 10-4 ev2 KamLAND can observe
  oscillation signature, if Dm2 gt 1 x 10-4 ev2 need
  new experiments
• Low masses Need better Q12 gt SNO, Low E
  Solar, KamLAND II
• High Masses, still need oscillation signature
  and need better Q12 gt HLMA experiments for Dm2
  SNO, Low E Solar, KamLAND II also will seek
  oscillation signatures
• LSND confirmed or refuted (miniBOONE) if
  confirmed gt Sterile n
• Sterile Neutrinos gt BOONE
• Sterile Neutrinos gt Low E Solar
• (If) Neutrino Oscillations
• Full MNS matrix needs to be filled out - Mixing
  Parameters gt SNO, Low E Solar, KamLAND, LBL, 7Be
  expts., Minos, miniBOONE, JParc, Off-axis expts,
  q13 reactor experiments
• Neutrino Nature
• Majorana or Dirac? (DbD, Cuore, Majorana)
• Mass Scale
• Absolute mass scale? (Katrin tritium bD, DBD)
• Less likely (harder) after WMAP

SNO NC