Takasumi Maruyama (KEK)
Thanks to J.Spitz (U of Michigan)for KPIPE experiment discussion

indication of the sterile neutrino (Dm2~1eV2) ?
• Anomalies, which cannot be explained by standard
neutrino oscillations for ~20 years are shown;
Experiments

Neutrino source

signalsignificanceE(MeV),L(m)LSND

m Decay-At-Rest

nm  ne

3.8s

40,30

MiniBooNE

p Decay-In-Flightnm  ne

3.4s

800,600

nm  ne2.8s

combined

3.8s

Ga (calibration)e capturene  nx

2.7s<3,10Reactors

Beta decayne  nx

3.0s3,10-100• Excess or deficit does really exist?
• The new oscillation between active and inactive (sterile)
neutrinos?

Neutrino oscillations with Dm2~1eV2 regioné n ù é U
ê e ú ê e1
ê n ú ê U
ê m ú ê m1
ê n ú=ê U
ê t ú ê t1
ê ns ú ê Us1
ú êêêë · úû êë ·Ue2 Ue3 Ue4 · ùúé n ù
ê 1 ú Matrix elements,
Um2 Um3 Um4 · úê n ú which are consideredúê 2 ú in 3x3 mixing
Ut2 Ut3 Ut4 · úê n3 ú framework.
úêú
Us2 Us3 Us4 · úê n4 úúêú· · úê · ú··ûûë(3+1) modelMauro Mezzetto’s(experimental summary)talk in Neutrino2016

 Checking higher Dm2 w/

nm disappearance
 KPIPEnm  nmne  ne+nm  nm

3+1 model checking

ne  ne Is it time to check the LSND result
directly w/o any excuses?
 JSNS2ne  nene  neMauro Mezzetto’s(experimental summary)talk in Neutrino2016

nm  ne (horn focused beam)J-PARC Sterile nsearch @MLF
400MeV

J-PARC Facility(KEK/JAEA）
South to North

3 GeV RCS

Neutrino Beams(to Kamioka)

25Hz, 1MW (design)

Materials and Life
Science Experimental
Facility (MLF)

CY2007 Beams
JFY2008 Beams
JFY2009 Beams

Hadron hall
Bird’s eye photo in January of 2008

Direct ultimate tests for LSND.
Collaboration meeting @ KEK(2017/May/11-12)

JSNS2 collaboration (53 collaborators)• 10 Korean institutions (18 members)• 6 Japanese institutions (28 members)• 5 US institutions (7 members)

7

JSNS2 setup at J-PARC MLF
MLF building (bird’s view)

Detector @ 3rd floor(24m from target)

Hg target = Neutron
and Neutrino source

17t Gd-loaded liquid scintillator(4.6mf x 3.5m h)
193 8” (inner)+ 48 5” PMTs (veto)
image

3GeV pulsed
proton beam

Searching for neutrino oscillation : nm  ne with baseline of 24m.
no new beamline, no new buildings are needed  quick start-up

Production / Detection• Large amount of parent m+ in Hg target  nm are produced.
• If sterile n exist, nm  ne oscillation is happened with 24m.
• Oscillated ne is detected by Inverse Beta Decay (IBD): ne + p  e+ + n w/ wellestablished detector technique(E resolution = 15%/sqrt(E))

3GeV
pulsedprotonbeam

Most of them
are same as
The LSND.
 Direct ultimate
tests for LSND.

(Decay-at-Rest)
Scintillation lightp+

IBD criteria

TimingEnergy

Prompt1<Tp<10μs

20<E<60MeV

DelayedTp<Td<100μs

7<E<12MeV<T>~30ms

Scintillation light(~ 8MeV In total)

But use muchbetter beam andGd loaded LS.
 Much better
S/N Much bettersystematics
9Timing and Energy

M. Harada et al, arXiv:1310.1437
Next beam is 40ms laterp timing

Selecting muon decay(e~74%)

Timing and Energy are friends of JSNS2➢ Timing: Ultra-pure n from m+ Decay-at-Rest➢ n from p and K -> removed with timing➢ Beam Fast neutrons -> removed w/ time
➢ Cosmic ray BKG -> reduced by 9ms time window.

➢ Energy: signals / BKG separation by energy.

➢ n from m has well-known spectrum.
➢ Energy reconstruction is very easy at the IBD. (En~ Evis + 0.8MeV)➢ n from m- is high suppressed.

10IBD event selection
casen capture
2; Prompt signal E cut

3. Delayed gamma E cut

4. Distance cut betweenprompt vertex anddelayed vertex
4. Dt cut between promptand delayed(~30ms lifetime for n )Selection e~ 38%#events (1MW x 3 years x 1 detector (17tons))
Sourcecontents#ev.(17tons x 3years)

Reference : SR2014(50tons x 5 years)

comments

backgroundne from m-43237

Dominant BKG

12C(n ,e-)12N
eg.s.

3

16

Beam fast neutrons

Consistent with 0< 2 (90%CL UL)<13

Fast neutrons (cosmic)~037

Accidental

2032

Based on real data

87480

Dm2=2.5, sin22q=0.003

62342

Dm2=1.2, sin22q=0.003

signalBased on real data

Accidental BKG is calculated by;R acc = SRprompt x SRdelay x DVTX x N spill
MLF best Dm2(2.5eV2)– SRprompt, SRdelay are probability of accidental BKG for prompt and delayed.
– DVTX ; BKG rejection factor of 50.
12– Nspill(#spills / 5 years) = 1.9x109

Sensitivity / Upgrade• To have a good international competition capability, we start the experiment with
one detector (17tons fiducial volume).
• Even with one detector, we have a good 90% C.L constraints for the best fit point of
global fit (of sterile neutrino searches) for 3 years. Left plot
• Meanwhile, we are making effort to obtain the budget to build the 2nd detector. (andenlarged acrylic tanks). This upgrade can make 5s significance test for the best fit
point of the global fit.

IceCube+SBL allowed (90%)
99% from arXiv 1607.00011v2

3 years x MW x 17 tons

5 years x MW x 50 tons

Achievements so far• 2013 Sep; A proposal was submitted to the JPARC PAC• 2014 Apr-Jul; We measured the BKG rate on
3rd floor. -> manageable beam /cosmic BKGs
to perform JSNS2PTEP 2015 6, 063C01 / arXiv:1502.02255• 2014-Dec; The result was reported to J-PARC
PAC.  the stage-1 status was obtained fromJ-PARC /KEK
• The performance check of detector andsafety discussions are being performed.
• 2016-June: The grant-in-aid was approvedfor one detector construction• 2017-May: Technical Design Report wassubmitted to J-PARC PAC and arXiv(arXiv:1705.08629 [physics.ins-det] )• We aim to start JSNS2 in JFY2018

2014BU1301
experiment (@MLF 3rd floor)
Proton beamSignal region for
IBD prompt signal
BKG ~ 0

14Energy (MeV, vertical) vs timing (ns, horizontal)

Schedule & Status
cf.:SBN possible starting time(1) A stainless tank will be produced in JFY2017. (2) PMTs can be made within a half of year.
(3) The bid for the acrylic tank will be started soon. (4) LS will be produced at Korea.

KPIPEnm  nm is also important.

17KPIPE

Axani, Collin, Conrad, Shaevitz, Spitz, Wongjirad, Phys Rev. D 92 092010 (2015)

The idea:
Use a very long liquid scintillator detector to look for νμdisappearance (in L) using 236 MeV KDAR νμ CC events@ J-PARC MLF

Long LS detector surrounded by SiPMs

KPIPE

Axani, Collin, Conrad, Shaevitz, Spitz, Wongjirad, Phys Rev. D 92 092010 (2015)

A very pure flux of KDAR neutrinos!

No beam timing cut

The beauty of KPIPE
If you detect a numu CC event, you can be 98.5% sure that it
was a 236 MeV muon neutrino!

Since you know the energy of the neutrino, you don’t need to worry about
energy resolution. KPIPE calls for 0.4% photocoverage.
Estimated cost of experiment: $4.5M
KPIPE cost document: http://hdl.handle.net/1721.1/98388

20KPIPE; what would a signal
look like?

KPIPE sensitivity• 6 years of running• Extends limit at high-Δm2 by anorder of magnitude.

• Highly complementary to SBN
program.

• 6 years of MicroBooNE• 3 years of T600 and SBND.

Summary• There are fascinate programs for sterile neutrino searches at JPARC MLF.  large number of neutrinos are produced at themercury target.
• JSNS2 : Direct test for the LSND anomaly without any excuses (nmne)• Using ultra pure m Decay-At-Rest neutrinos due to nice beam timing.
• Gd loaded LS.
• Improves S/N (by more than 100) and systematic uncertainties.
• Budget to build one detector was granted in 2016.
• Technical Design Report (TDR) was submitted to PAC and arXiv:1705.08629.
• Aim to start the experiment in JFY2018.

• KPIPE: nm disappearance experiment• Using 236 MeV monochromatic neutrinos from Kaon Decay-At-Rest.
• Oscillation curve can be seen as a function of L. (E is one number.)• Comparable sensitivity as SBN program with reasonable cost.
• Letter of Intent (LoI) was submitted to J-PARC PAC (in 2016).

backupne  nene  ne

 Is it time to check theLSND result directly without
any excuses?
 JSNS2
Mauro Mezzetto’s(experimental summary)talk in Neutrino2016

nm  ne (horn focused beam)

Appearance

LSND

me Signal

1998

c

43

600ms 120Hz
target+beam stop
configuration
DIF, n bkg.
p  m + nmm e + ne + nm

² + # m +! m nee +! e! mOscillations?

!ep-, LSND
m- absorbedbeforedecay
into n’s andin conjunction
withthe atmospheric-4
thereshould
not bene needs
at themore
levelthanof 7x10
solaroscillation
results
3 n’s
Þ Models developed with 1 or 2 sterile n’s

Signal : ne p→e+n np→d g(2.2MeV)

Saw an excess of:
87.9 ± 22.4 ± 6.0 events.
With an oscillation probability of(0.264 ± 0.067 ± 0.045)%.
3.8 s evidence for oscillation.

Trial by MiniBooNE @ Fermilab

Chris PollyNEUTRINO2012• Horn focused beam has many backgrounds Ke3, m decay, p0 production• En reconstruction; claimed to have issues by nuclear effects

8” PMT pre-calibration
8” PMT pre-calibration (by Kitasato)

There are almost consistent
with Hamamatsu evaluations.

Examples of measurement
7ADC distribution The HV of 10 -gain was applied.
Peak=634.73
Valley=197.12⇒ P/V=3.22#Entries

Test PMT

Light source:
Pico-second Laser+ Diffuser

Test item:
Gain, Peak-to-Valley ratio, Transit time spread, QE×CE
Status:Test conditions are adjusting using an 8”PMT sample.
- Light intensity, PMT position, etc…

×106

Gain curve