The JSNS2 experimentJungsic Park (KEK)
計測システム研究会, Nov 26-27
Jungsic Park, KEK

1J-PARC Sterile Neutrino Searchat J-PARC Spallation Neutron Source
Collaboration meeting @ J-PARC (2020/Feb)

JSNS2 collaboration (61 collaborators)- 6 Japanese institutions (27members)- 10 Korean institutions (26 members)- 1 UK institution (1 member)- 4 US institutions (7 members)

JAEA
KEK
Kitasato
Kyoto
Osaka
TohokuSoongsil
SussexDongshin
GIST
Seoyeong
Chonnam National
Seoul National

Alabama
BNL
FloridaMichiganJungsic Park, KEK

Contents- Introduction of the JSNS2experiment- DAQ system- Quick glance of the dataIndication of a sterile neutrino (Δm2~1eV2)Experiments

Neutrino source

LSND
MiniBooNE

signalsignificanceE(MeV), L(m)μ Deacy-At-Rest

3.8 σ

40, 30π Decay-In-Flight

4.5 σ

800, 600

2.8 σ
arXiv:1805.12028

combined

4.8 σ+ LSND

6.1 σ

Ga (calibration)e capture

2.7 σ<3, 10Reactors

Beta decay

3.0 σ

1-8, 10-100• Excess or deficit do really exist?
• Note: JSNS2 uses the same neutrino source (μ), target (H) and detection principle (IBD)
as the LSND à even if this is not due to the oscillation, we can catch this directly

J-PARC MLF：one of the world best environments
Detector @ 3rd floor(24m from target)

LSHg target = Neutron
and Neutrino source

Gd-LS

3GeV pulsed
proton beam

• Searching for neutrino oscillations over a 24m baseline• do not need new beam-line or building è started !!
Jungsic Park, KEK•••

52t (Gd-loaded + unloaded)liquid scintillator detector
4.6m diameter x 4.0m height120 10” PMTs4Production / Detection
Most of them aresame as the LSND.
à Direct ultimate
tests for LSND.

3GeV pulsed
proton beamΔt ~ 30 μsTimingEnergy

Prompt1 <Tp<10μs

20<E<60MeV

DelayedTp<Td<100μs

7<E<12MeV

Jungsic Park, KEK

But use muchbetter beam andGd loaded LS.
à Much better S/Nà Much bettersystematics

5

Energy Spectrum and Sensitivity (by MC simulation)• Left: Energy spectrum （Δm2 = 1.2eV2, sin22θ = 0.003)• Right: Sensitivity of 3 years physics running of JSNS2 with one detector.
JSNS2 best case

MW x 3 years(x 1 detector)

Jungsic Park, KEK

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Detector construction (2017 – 2020)
Detector construction have been
finished in February 2020.
••
•

•
••
•

Stainless steel tank was producedby Morimatsu (2017-2018) JINST 14 (2019) no.09, T09001
Acrylic tank was produced by Nakano(2018-2019)
10 inch PMTs from collaborators• RENO / Double Chooz
JINST 15 (2020) no.07, T07003• And newly purchased
35 tons of LS was produced by
Korean collaborators (2018) JINST 14 (2019) no.09, T09010
17 tons GdLS was donated by Daya-Bay (2019)
Electronics were reused or donatedby Double Chooz JINST 15 (2020) no.09, T09002
Fast LED system

Very efficient experiment using reused or
donated materials from various experiments.
We do appreciate Daya-Bay, RENO and DC.

Detector operation cycle• MLF 3rd floor is the maintenance area for the mercury target and beamequipment. Thus, we need to bring in and out the detector during summer
beam shutdown every year (4 months).
• I.e. : we have to fill in and extract out (Gd)LS during short time also.
① Move the detector from detector assembly building (HENDEL) to MLF② Scintillator filling in MLF 1st floor within 10 days
③ Data taking in MLF 3rd floor (1st physics run during 6/5 – 15 June 2020)④ Scintillator extraction again in MLF 1st floor within 10 days again.
⑤ Move the detector to HENDEL
Jungsic Park, KEK

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targetCatcher+ Veto

1st data taking:6/5–6/15(stable (Gd)LS operation)

Move detector to MLF

Scintillator filling

World fastest speed !!
Veto PMTs

Detector on the MLF

Data taking

Event display

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1st physics run
We took 1st physics data in June- with 28 CAEN FADCs and 4 optical links- one DAQ PC and one Data quality
monitoring (DQM) PC- Triggered by the Beam- LED- self-trigger (including 252Cf)- Several test runs for the next round- Data is transferred to KEKCC< Data flow from the DAQ PC to KEKCC >10

DAQ + DQM
500 MHz FADCs (V1721) are donated from the DC.
- Arrived in Jan 2019.
- Optical link daisy chain (80MByte/each).
We transfer data with TCP / IP socket to the DQM PC.
- 1Gbps between the DAQ and the DQM PC- Adler 32 is used to check the transfer status.

Consists of header, body, and trailer.
Header Size
Run Number
Trigger Time Tag
Event Number
Header magic, NBOARDSFADC 1 Serial ID

DQM PC- Installed CentOS 7- Has 12 TByte storage- FADC raw data is stored in the DQM storage,
compressed, and then transferred to the KEKCC.
with 1Gbps ethernet.
- Monitoring the data quickly.
- Conversion of the data to the ROOT format.

FADC 1 data
FADC 2 Serial ID
FADC 2 data
FADC 3 Serial ID
FADC 3 data....... (FADC Information)
Trailer magic

11Beam Trigger Timing from the collisionof the proton to mercury target
4V150 ns
< Kicker >4V150 ns

150 ns< CT >

Current Transformer (CT) induced eventfrom magnetic field changing.
- Available from the MLF- Can confirm the beam “really” came or not

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JINST 15 (2020) no.09, T09002

DAQ scheme
FEEs
8 PMTs

8 high-gains

FADCs

High-gain ×16
Low-gain × 0.6

A total of
120 PMTs

8 ch analog sumof the high-gain

8 low-gains

FADCs

FADC

A total of
28 FADCs

analog sum
1/6
Attenuators

Analog sumTrigger
BoardDigital
Fan-in/out
BeamTriggeropticallinks

DAQ
Computer

DQM
Computer

KEKCC

Using special amps with twodifferent gains.
- high-gain for the low energy- low-gain to increase thedynamic range- analog-sum of 8 high-gain
channels
Assigned one FADC board
as a “trigger board”.

13Trigger
We used “external triggers” to store the PMTs waveforms.
- Designated “a FADC Trigger board” to generate a global trigger.
- LED : The controller box generates a external NIM trigger.
- Kicker : Accelerator group provides with a TTL trigger.
- self (including 252Cf) : Use the analog sum of inner PMTs waveform.
- Each trigger type can be distinguished with a trigger bit.
Trigger board

Digital Fan in / outNIM

TRG-OutinTRG-In
ch 0...

LED / kicker /delayed kicker /analog sum /CT...........

Trigger in

TRG-in of each FADC
(total 28 FADCs)
to store the PMTs waveform.

ch 714

FADC timing synchronization••••

Each FADC is equipped with aninternal clock
The clocks across the FADCs will,in general, be out of phase
FADC’s clock is synchronizedusing a daisy chain method
Trigger board serves as amaster clock•

In the oscilloscope screenshot,
one can see the clock phasebetween the master clock (yellow)
and each board (violet).

•referred “AN2086 – synchronizationof CAEN digitizers in multiple board
acquisition systems”
Jungsic Park, KEK

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Monitoring of the data taking status

Trigger rate

Run Status
Jungsic Park, KEK

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Data quality monitoring (DQM) plots
The DQM PC produces useful plots- PMT raw waveform(Both the high/low gain)- Trigger bit- Will add more plots to the next

PMT rawwaveform

high-gain (16)low-gain (0.6)

CT (50 Hz)
Kicker (25 Hz)
Jungsic Park, KEK

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Beam power / POT
Average Beam power: 602kW (4.97 x 1013 POT/spill)
We have mini beam maintenance period on every Wed.
- June-10: 24 hours mini-shutdown.
- Used for the calibration campaign (LED, 252Cf, run w/o beam)
8.46 x 1020 POT for the 1st physics run- 0.8% of approved POT (by J-PARC PAC)
- Less than 1 IBD event are expected.
- However, our detector is working well, and JSNS2 shows
strong potential from the next physics run.
(from early of next year)

Detector calibration

J-PARC and MLF aims to have a design beam power (1MW)
as soon as possible and have succeeded the test from June-25 to 27.
Jungsic Park, KEK18

DAQ Efficiency

Total Efficiency : 94.5 %(215.8 hour / 228.3 hour)

Gate scan
self-trigger test
2.9 %

2.6 %

LED / Cf
Running
HV exchange
Setup change

HV exchange(~ 6 hours)

LED

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252Cf calibration data (source is put on center)Can see clear excess due toneutron capture on Gd.

Excess by 252Cf source

Detector is working well.
w/o 252Cfw/ 252Cf

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Activities around beam timing
Two-bunch structure
is clearly seen.

First 30min data-> 46524 spills

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Summary•

JSNS2 aims to test the LSND anomaly directly.

+ Uses the same neutrino source (μ), target (H) and detection principle (IBD), but muchsmaller accidental background due to Gd-loaded LS and low duty factor J-PARC MLF beam.

•Just started data taking from 2020-June.

+ Operation (filling/extraction) of (Gd)LS have been very smooth without any issues.
+ With data taking for 10 days (0.8% of data compared to the approved POT),
we saw a good potential of this experiment as expected.
• response of neutron capture signal is clear.
• activities around beam timing looks as expected• similar to 2014 background measurements, and TDR.

•We plan to upgrade the detector and construct the 2nd detector+ Essential to improve the sensitivity+ Grant was approved !!
Jungsic Park, KEK22