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Neutrinos at the SNS (Spallation Neutron Source)

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Supper Neutrino Source Neutrinos at the SNS (Spallation Neutron Source) Yu.Efremenko ORNL 0. A little bit of Modern Neutrino History Why Low Energy Neutrinos are Good – PowerPoint PPT presentation

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Title: Neutrinos at the SNS (Spallation Neutron Source)


1
Neutrinos at the SNS (Spallation Neutron Source)
Supper Neutrino Source
Yu.Efremenko
ORNL
  • 0. A little bit of Modern Neutrino History
  • Why Low Energy Neutrinos are Good
  • 2. Some Proposed Neutrino Experiments at SNS

2
Lets Look Back in Time
The Earliest Neutrino Conference that has
Transparencies posted on the WEB is Neutrino 1998
Ten Years later
Yes !!! dm122 7.5810-5 eV2
sin2(2?12)0.87 SNO KamLAND
Yes !!! dm322 2.410-3 eV2 sin2
(2?23)1.00 SuperK, K2K, MINOS
MiniBoone left door open for some exotic scenarios
Two out of three done!!!!!
3
Now We Have New Set of Experimental Challenges
We have a long list of neutrino properties to
study. Neutrino Mass gt KATRIN Set of Double
Beta Experiments ?13 -gt DoubleChooz, Daya Bay,
T2K, NOVA CP phasegt Long Baseline
experiments At the same time we have to look
at what role neutrinos are playing in our
Universe. To do so we have to better understand
neutrino interactions with nuclei!
4
Man Made Neutrino Sources
Stop Pion Facilities 10ltEnlt53 MeV Very
interesting region. It is nicely coincides with
neutrino energies produced during the Super Novae
Explosion
In E-M LSNL galaxy In Neutrinos LSN 3000 L
galaxy
5
Core-collapse supernovae
  • Destruction of massive star initiated by the Fe
    core collapse
  • 1053 ergs of energy released
  • 99 carried by neutrinos
  • A few should happen every century in our Galaxy,
    but the last one observed was over 300 years ago
    (recently discovered 150 years old remnants of
    SN in M.W. G1.90.3)
  • Dominant contributor to Galactic nucleosynthesis
  • Neutrinos and the weak interaction play a crucial
    role in the mechanism, which is not well
    understood

SN 1987a Anglo-Australian Observatory
6
Neutrinos and Core Collapse SN
The weak interaction plays a crucial role in
supernova ! We need good understanding of
neutrino interactions !
7
Supernova Neutrino Observations
SN 1987A
High statistic measurement of neutrino signal
from SN will provide wealth of information about
SN dynamics
  • An accurate understanding of neutrino cross
    sections is important for SN neutrino detectors.
  • Nuclei of interest C, O, Fe, Pb

8
Diffuse Supernovae Neutrino (DSN) Detection
While waiting for SN to happen in the Milky Way
we can search for diffuse SN flux
From C.Lunardini, astro-ph/0610534
  • Several proposals are aiming to be sensitive
    enough to see DSN
  • GADZOOKS
  • HyperKamiokande
  • UNO
  • MEMHYS
  • LENA
  • LANNDD
  • GLACIER

9
Atmospheric Neutrino Background for DSN
Water Cherenkov detectors
SuperK 92 ktony
Irreducible background from atmospheric neutrino
interactions limit discovery potential.
Detectors with Neutron Detection Capabilities
Antineutrino Channel with neutron detection will
eliminate such a background
From LENA proposal Phys.Rev.D75023007 there is
claim of background free window from 10 till 25
MeV
However background from neutral current
reactions have not been considered yet. We need
good understanding of neutrino Carbon and
neutrino Oxygen interactions!!!
10
Neutrino Nuclear Interactions at Low MeV Range
are
Important for understanding of supernovae
mechanism Important for neutrino detection from
SN Important for Calculations of backgrounds for
DSN Have a general interest for the nuclear
theory
It is important to provide accurate v-A
measurements for wide range of isotopes
11
Early interest in low energy neutrino nucleus
cross sections
Twenty five years later, same scientist is still
interested in neutrino-nucleus cross sections
12
Neutrino Coherent Scattering
Detectable only via very low energy (10keV)
nuclear recoil
Never observed Important for supernova dynamics
(neutrino opacity)
13
What Physics Could be Learned From Neutrino
Coherent Scattering?
K. Scholberg, Phys. Rev D 73 (2006) 033005
Basically, any deviation from SM is
interesting...
- Weak mixing angle could measure to
few (new channel)? - Non Standard Interactions
(NSI) of neutrinos could
significantly improve constraints - Neutrino
magnetic moment hard, but conceivable
It is difficult to do it on Nuclear Reactors
because of the continues flux and very low recoil
energies
14
New Facility -SNS
15
SNS
1 GeV
Similar pulse structure to ISIS ? greatly
suppressed backgrounds
Presently being commissioned. 0.5 MW power has
been achieved last week
Eventual operation gt 1 MW (FY09)
7x1012 p / spill
(10x ISIS)
16
Accelerator
17
Target
18
Neutrino Production at SNS
CAPTURE
99
?e
Fragments
?-
? ? 2200 nsec
A
?
DAR
e
?
1 GeV
? ? 26 nsec
??
Fragments
Specific benefits of neutrinos at SNS
  • Well known neutrino spectra (DAR)
  • Separate neutrinos of different flavors by time
    cut
  • Very high neutrino intensities 1015 n/sec
  • Pulsed Structure

19
Potential Locations for Neutrino Experiments at
theSpallation Neutron Source
proposed site inside target building
  • 20 m2 x 6.5 m (high)
  • Close to target 20 m
  • 2x107 n/cm2/s
  • q165? to protons
  • lower backgrounds

The SNS Target hall
There are multiple sites available outside of
target building.
20
Background Studies
2.81020 protons delivered on target in two week
period 1020 neutrino produced
Power 0.4 MW
Now Background, shielding protoype studies
?p2 C
neutrons
Particle id
Counts
gammas
-2
2
4
6
0
Pulse height
Time (?s)
21
Possible Concept of Shielded Enclosure for
Neutrino Experiments
  • Total volume 130 m3
  • 4.5m x 4.5m x 6.5m (high)
  • Heavily-shielded
  • 60 m3 steel 470 tons
  • 1 m thick on top
  • 0.5 m thick on sides
  • Active veto
  • 70 m3 instrumentable
  • Configured to allow 2 simultaneously operating
    detectors of up to 40 tons
  • ?A coherent scattering
  • 43 m3 liquid detector
  • Segmented detector for solids
  • Prototypes for SN detectors

22
Cosmic Ray Veto
Sensitive to cosmic muons Blind for gammas from
(n , gamma) capture
23
Veto RD
  • In collaboration with MECO
  • 100 x 4.5-m planks extruded for ?SNS

23
24
Homogeneous Experiment
  • 3.5m x 3.5m x 3.5m steel vessel (43 m3)
  • 600 PMTs (8 Hamamatsu R5912)
  • ? Fiducial volume 15.5 m3 w/ 41 coverage
  • Robust well-understood design
  • ?dE/E 6
  • ?dx 15-20 cm
  • ?dq 5? - 7?

First experiments 1300 events/yr ne12C?12Ne-
(mineral oil) 450 events/yr ne16O ?16Fe-
(water) 1000 events/yr nx2H ? pn nx (heavy
water)
25
Performance
Geant4 Monte Carlo simulations ongoing
  • ?dE/E 6
  • ?dx 15-20 cm
  • ?dq 5? - 7?
  • Neutron discrimination?
  • Layout and coverage
  • More compact photosensors
  • 60 of mass lost to fiducial cut

26
Standard Model Tests
  • Shape of the ?e spectrum from ? decay is
    sensitive to scalar and tensor components of the
    weak interaction

µ ? e ?e ?µ .
?e 12C ? e- 12N g.s.
?SNS expected 1-yr operation
KARMEN upper limit
?L0.11
Armbruster et al., PRL81 (1998)
  • We could substantially improve the limit on ?L
    with only 1 year of data

?L0
27
Segmented Experiment
corrugated metal target
straw tube
16 mm
anode wire
Target - thin corrugated metal sheet (e.g. 0.75
mm-thick iron) Total mass 14 tons, 10 tons
fiducial Other good metal targets Al, Ta,
Pb Detector 1.4x104 gas proportional counters
(straw tube) 3m long x 16mm diameter 3D position
by Cell ID charge division PID and Energy by
track reconstruction Expected Statistic 1100
events/yr neFe?Coe- 1100 events/yr
neAl?Sie- 4900 events/yr nePb ?Bie-
28
Straw tube RD
  • Currently testing prototypes
  • Diameters between 10-16 mm
  • Lengths ranging up to 2 m
  • Gases (Ar-CO2, Isobutene, CF4)
  • Measure resolution with cosmic muons
  • Energy, position, time
  • How much can time resolution be improved using
    pulse shape information?
  • Simulations to improve the fast neutron
    discrimination.

29

The CLEAR (Coherent Low Energy A Recoils)
Experiment
30
CLEAR
A. Curioni
31
Background for CLEAR
Expect 190 events/year in 20 kg of xenon gt3
keVr
SNS neutronics group calculation of neutron
spectrum Fluka sim through shielding (T.
Empl) Xe detector sim (J. Nikkel)?
scaling using measured fluxes
32
Osc-SNS
Sterile Neutrinos Neutrino Oscillations Test CP
Violation
  • MiniBooNE/LSND-type detector
  • Higher PMT coverage (25 vs 10)
  • Mineral oil scintillator (vs pure oil)
  • Faster electronics (200 MHz vs 10 MHz)
  • Located 60m upstream of the beam dump/target,
    this location reduces DIF background

60m
33
Oscillation Event Rates
Beam Width SB Osc. Candidates
LSND ?? ? ?e 600 ?s 11 35 (observed R gt 10)
FNAL ?? ? ?e 600 ns 13 400
SNS ?? ? ?e 695 ns 51 448/year
Expected for LSND best fit point of sin22?
0.004 dm2 1
34
Summary Outlook
  • Understanding of neutrino interactions are
    important for
  • Physics of Supernova
  • Calculation of response of Large Neutrino
    Detectors to Milky Way Supernova
  • Calculation of backgrounds from DSN
  • The combination of high flux and favorable time
    structure at the SNS is very attractive for
    diverse program of neutrino studies
  • New Proposals like CLEAR and Osc-SNS appeared
    recently
  • We welcome new ideas and participation
  • See http//www.phy.ornl.gov/nusns
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