Super­Kamiokande Gadolinium R&D Project: 

Introduction and Overview

JPS Spring meeting. Sendai, Tohoku Gakuin, 21st March, 2016.

Lluís Martí Magro (Kavli IPMU, University of Tokyo)for the Super-Kamiokande Collaboration.

Supernova relic neutrinos (SRN) are those neutrinos from all the past core collapse supernovae in the history of the universe.

Phys.Rev. D 79, 08013 (2009)

2

Nuclear reactors

Super-K

Cosmic rays...

… produce μ and ν

Mt Ikena

Primary Motivation

Supernova relic neutrinos (SRN) are those neutrinos from all the past core collapse supernovae in the history of the universe.

Phys.Rev. D 79, 08013 (2009)

3

Primary Motivation

Flux limit at Super-K

Phys. Rev. D 85, 052007 (2012)

→ Large backgrounds dominate this analysis.→ Measurement limits are getting closer to predictions.→ Expand the energy range starting from 10 MeV.

Supernova relic neutrinos (SRN) are those neutrinos from all the past core collapse supernovae in the history of the universe.

Phys.Rev. D 79, 08013 (2009)

4

Primary Motivation

Flux limit at Super-K

Phys. Rev. D 85, 052007 (2012)

The main goal is the discovery of SRN !

Supernova Relic Neutrino: How to

ep

n

e+

42º(Not efficiently detected, no neutron tagging used)

γ (2.2 MeV)p

Pure water

5

With Tight time (delayed) and position coincidence between positron and neutron capture (90% neutron capture on Gd with 0.2% Gd

2(SO

4)

3 concentration) we will be

able to reduce backgrounds and detect SRN for the first time!

Idea proposed as GADZOOKS!by Beacom & Vagins PRL.93, (2004) 171101

- Easy to dissolve- Good optical properties- Compatible with detector components

Supernova Relic Neutrino: How to

γ

ep

n

Gd

e+

8 MeV cascade

42º

p

n

e+

42º(Not efficiently detected, no neutron tagging used)

γ (2.2 MeV)p

Pure water Gd-loaded water

6

@ EGADS has shown that:

e

200 m3 detector tank

15 m3 tank Water circulation system(band pass-filtration system)

EGADS Evaluating Gadolinium’s Action on Detector Systems

Transparency measurement

(UDEAL)

7

After full Gd loading the water transparency is within typical SK values Gd

2(SO

4)

3 is compatible with the detector components8

Gd loaded water attenuation

Power failure

Accidental contamination

Gd concentration

Fast and homogeneous dissolution inside the EGADS detector.Constant concentration since full loading (end of April 2015)9

25/Nov25/Dec

24/Jan23/Feb

25/Mar24/Apr

24/May23/Jun

23/Jul22/Aug

21/Sep21/Oct

20/Nov20/Dec

19/Jan18/Feb

0

500

1000

1500

2000

Sampling date

Co

nce

ntr

atio

n [

pp

m]

Top

Centre

Bottom

Sampling position:

20152014

EGADS Gd (SO ) + x · H O concentration₂ ₄ ₃ ₂

Official statement

SuperK-Gd is moving forward!!

On June 27, 2015, the Super-Kamiokande collaboration approved the SuperK-Gd project which will enhance anti-neutrino detectability by dissolving gadolinium to the Super-K water.

The actual schedule of the project including refurbishment of the tank and Gd-loading time will be determined soon taking into account the T2K schedule.

SK/T2K “SK­Gd” official statement

On June 27, 2015, the Super-Kamiokande collaboration approved the SuperK-Gd project which will enhance anti-neutrino detectability by dissolving gadolinium to the Super-K water.

T2K and SK will jointly develop a protocol to make the decision about when to trigger the SK-Gd project, taking into account the needs of both experiments, including preparation for the refurbishment of the SK tank and readiness of the SK-Gd project, and the T2K schedule including the J-PARC MR power upgrade. Given the currently anticipated schedules, the expected time of the refurbishment is 2018.

PMT, electronics and DAQ

12

Exhaust pipe

To outside(Mixed with air from A/C)

Input Air

Input Air

- DAQ runs with very high livetime- Temperature stable within ~1º C- Auto shutdown system in case of emergency

- DAQ and slow control monitor checksevery 2 hours by shifters. - compensation coils - PMT HV - DAQ status

- Automated warning emails to experts in case of problems

Front-end and DAQ PCs

ATMs

Next: electronics upgrade

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- QBEE front-end electronics:QTC (Charge to time converter) Based Electronics with Ethernet.Data transfer capability enhanced by using Ethernet.Capability for higher event rates (~ few MHz)All hits can be collectedSoftware trigger can be applied

EGADSDAQ

Summary and OutlookEGADS detector running with full Gd loading since end of April 2015

After reaching the final concentration of 0.2% of Gd2(SO

4)

3 in the EGADS

detector we have shown that:

→ Very good water transparency in the EGADS detector

→ No Gd2(SO

4)

3 losses and homogeneous Gd dissolution

SuperK-Gd project approved and moving forward!!

DAQ and electronics taking data and stable.→ Working on the electronics upgrade to have full galactic ccSN coverage.

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Next talks: Am/Be calibration in EGADS by Xu Ra/Rn system by Ito Rayleigh scattering MC by Akutsu

Thank you for your attention!!

July 7th, 2010

Current ATM front­end electronics

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Current front-end electronics are based on the old Super-K Analog Timing Electronics (ATM) modules.

- 12 input channels/board. When PMT signal is above the threshold a “hit” signal is issued (15 mV height and 200 ns width)

- A HITSUM is defined as the analog sum of all these hits from all ATMs.

- When the sum exceeds a threshold then a global event trigger is issued. Only the hits within this time window are transferred to on-line computers.

→ Data transfer between front-end electronics and on-line computers is the bottleneck in our current system: UPDATE is NEEDED for high event rate recording

EGADS & plan schedule

- Step 1: Circulation through the 200 ton tank with pure water (no PMTs)- Step 2: Circulation through the 15 ton tank with Gd2(SO4)3 - Step 3: Circulation though the 200 ton tank with Gd2(SO4)3 loaded water- Step 4: PMT mounting (240 in total)

- Step 5: Full realization of the EGADS project Done!

Done!

Done!

Done!

Done!

17

18

PMT, electronics and DAQ

reformatter

Event displayEvent display & muon rate

- Long livetime, stable run

- Event rate ≈ 25 Hz

- Muon rate: 0.041 Hz(in agreement with estimations.Rough selection so far Nhit > 200)

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Muon/5 min

ATM vs QBee

20

More sophisticated/flexible triggering can be implemented.

EGADS

valuatingadolinium’sction onetectorystems

EGADS

mployingadolinium toutonomouslyetectupernovas

Cross sections

22

EGADS:- Betelgeuse ~90.000 events.- G.C. ~40 events.

Super-K:- Betelgeuse tens of millions events.- G.C. ~10000 events.

Sampling positions at 1660 mm, 3320 mm and 4990 mm from top of the tank (for water transparency, UDEAL, and Gd concentration measurements)

Inside the EGADS detector

6025

mm

1326

mm

1660

mm

3320

mm

4990

mm

to water system

from water system

1326

mm

PMTs were installed in summer 2013

23

Measuring Gd concentrationAtomic Absorption Spectrometer (AAS) Scheme:

Magnetic field

Hollow cathode lamp

Atomizer

24

Water transparency: UDEAL

Pulsed laser pointers and professional diodes

Pipe length: 8.6 mPipe diameter: 22.5 cm

Measurements at different heights

UDEAL: Underground Device Evaluating Attenuation Length

Integrating spheres and UV enhanced photodiodes

15 ton tank

Adjustable mirrors

Beam splitter & Steerer

Wave lengths: 337nm, 375nm, 405nm, 445nm, 473nm, 532 nm and 595nm

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Water transparency: UDEAL

Adjustable mirrors

Pulsed laser pointers and professional diodes

Beam splitter & Steerer

I/I 0

Integrating spheres and UV enhanced photodiodes

I [a

rbit

r. u

nits

]

Water height

26

Adjustable mirrors

Pulsed laser pointers and professional diodes

Beam splitter & Steerer

Integrating spheres and UV enhanced photodiodes

I [a

rbit

r. u

nits

]

Water height

Water transparency: UDEAL

27

Adjustable mirrors

Pulsed laser pointers and professional diodes

Beam splitter & Steerer

Integrating spheres and UV enhanced photodiodes

I [a

rbit

r. u

nits

]

Water height

Water transparency: UDEAL

28

Water transparency

WL [nm]

Measuring the water attenuation length for each wave length we get the following profiles for pure water and Gd loaded water:

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Water transparency

WL [nm] WL [nm]

WL [nm]

The Cherenkov light we detect is the convolution of:- Cherenkov spectrum- Absorption length of water- PMT Quantum Efficiency

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Motivation and introduction

The water attenuation length measured at different wave lengths, Li=L(λi), are weighted according to the Cherenkov light composition

Cherenkov light left @ 15 m

For the 7 wave lengths(337nm, 375nm, 405nm, 445nm, 473nm, 532 nm and 595nm)

Σ wi exp(-15 m/Li)

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Uncertainties

The uncertainty on the % of Gd capture is less than 0.9% (max. at 0.02% of gadolinium sulfate considering 3.5% uncertainty from the AAS)

0 0 0.02 0.20

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

Gadolinium sulfate concentration [%]Ca

ptu

re o

n G

d u

nce

rta

inty

(A

AS

: 3.5

%)

0.0020.0002 0.002 0.02 0.2

~0.3% uncertainty at 0.2% Gd2(SO4)3

0 0 0.02 0.20

10

20

30

40

50

60

70

80

90

100

Gadolinium sulfate concentration [%]

Ca

ptu

re o

n g

ad

olin

ium

[%]

0.0020.0002 0.002 0.020.0020.0002 0.002 0.020 0 0.02 0.20

10

20

30

40

50

60

70

80

90

100

Gadolinium sulfate concentration [%]

Ca

ptu

re o

n g

ad

olin

ium

[%]

0.0020.0002 0.002 0.020.0020.0002 0.002 0.02

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Loading Gd in the 200­ton tank

15 m3 tankCirculation

system

Gd removal

resin

pre-treatment

MembraneFlushing system

window

stirrer

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Loading Gd in the 200­ton tank

15 m3 tank

Gd removal

resin

pre-treatment

MembraneFlushing system

window

stirrer

Circulation

system

34