Title: Neutrinos at the SNS (Spallation Neutron Source)
1Neutrinos 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
2Lets 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!!!!!
3Now 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!
4Man 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
5Core-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
6Neutrinos and Core Collapse SN
The weak interaction plays a crucial role in
supernova ! We need good understanding of
neutrino interactions !
7Supernova 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
8Diffuse 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
9Atmospheric 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!!!
10Neutrino 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
11Early interest in low energy neutrino nucleus
cross sections
Twenty five years later, same scientist is still
interested in neutrino-nucleus cross sections
12Neutrino Coherent Scattering
Detectable only via very low energy (10keV)
nuclear recoil
Never observed Important for supernova dynamics
(neutrino opacity)
13What 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
14New Facility -SNS
15SNS
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)
16Accelerator
17Target
18Neutrino 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
19Potential 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.
20Background 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)
21Possible 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
22Cosmic Ray Veto
Sensitive to cosmic muons Blind for gammas from
(n , gamma) capture
23Veto RD
- In collaboration with MECO
- 100 x 4.5-m planks extruded for ?SNS
23
24Homogeneous 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)
25Performance
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
26Standard 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
27Segmented 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-
28Straw 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
30CLEAR
A. Curioni
31Background 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
32Osc-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
33Oscillation 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
34Summary 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