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
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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
13
- 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!
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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
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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
33
Loading Gd in the 200ton tank
15 m3 tank
Gd removal
resin
pre-treatment
MembraneFlushing system
window
stirrer
Circulation
system
34