danss v.egorov egorov@jinr.ru jinr (dubna) + itep (moscow) КАЭС
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DANSS
V.Egorovegorov@jinr.ru
JINR (Dubna) + ITEP (Moscow)
КАЭС
1.Neutrino monitoring of an industrial reactor• Power monitoring• Fuel composition• Tomography (?)…
2. Search for short-range neutrino oscillations
SPb
Moscow
Dubna
JINR
KNPP285 km
164 km
Participants of the NANPino-2013 workshop (Valday, June 2013) visiting the DANSS site at KNPP
Service room
mmm
3 000 MWth ВВЭР-1000
info
(1946)
Fraction of fissions
Time after beginning of operation period, days
Direct detection of the reactor neutrino would allow:
• Measure the actual reactor power (Nν)
• Deduce the actual fuel composition (Eν)
• Non-proliferation (prevent unauthorized extraction of 239Pu)
• Weak (ν-e) cross-section• On-line reactor monitoring (tomography?)
0.0
6.6
10.7
19.6
h
Reservoirs withtechnological liquids(cooling pond, boric acid, etc.)
Core:h =3.50 = 3.12
DANSS on a movableplatform with a lifting gear. flux 5 1013 / cm2 / sOverburden ≈ 50 m w. e.
Typical reactor buildingwith WWER-1000
m
Forbidden to use dangerous materials (LS) nearby the reactor
Segmental solid
plastic scintillator
(2500 cells)
Sensitivevolume=1
m3
Cu (carriage frames = -shield)
CH2 + B (n-shield)
Pb(-shield)
Plast. scnt.(µ-veto)
DA N
SS
0.150.30
40
1000
10
Basic element – - scintillator strip (1×4×100
cm)
Gd-containing light-reflecting
coating
Polystyrene-based
scintillator
3 wave-length shifting (WLS) fibers Ø1.2 mm
Conception of the detector: modular structure
2500 strips are combined into intercrossing X- and Y-modules (2020100 cm), thus providing not only energy information but also space pattern of each event.
PMT
PMT
100 WLS fibers(2 per strip)
X-ModuleY-Module
50 MPPC
100 WLS fibers(2 per strip)
50 MPPC
11
L = 12.2 m L = 9.8 m
Expected parameters:• Sensitive volume : 1 m3 =100×100×100 cm • Scintillator: Polystyrene based ( ~7.7 %wt of H)• Structure: (25 X + 25 Y) intercrossing modules =2500 strips
1 module 20×20×100 cm = 50 parallel strips• Mass with (CHB+Cu+Pb)-shield: 16-18 tonnes• Site: reactor unit#4 of Kalinin NPP (standard industrial WWER-1000,
Ø3.12 x h3.50 m, 3000 MWth)
• Reactor–Detector distance : 9.8–12.2 m (variable on-line) • Count rate: (10 000 IBD + 50 BG) /day @11 m• Energy resolution @ E =4 MeV: 25% (FWHM)
0 2 4 6 8 10
Energy, MeV0
1000
2000
3000
4000
235U MC simulation
L = 09.8 m
no oscillations
"French osc."
L = 11.0 m
L = 12.2 m
• Unfortunately, design and creation of the lifting system took longer time than expected. (Nonstandard equipment: must be certified!...)
• Moreover, its mounting near the reactor was allowed to be done only during the fuel recharge period (when the reactor is OFF).
• 2-years delay… But we did not loose our time!
Pilot version :2 modules of 50
= 40 kg =1/25th of DANSS
Simplified light collection (2 PMT only, no MPPC) Simplified electronics (4 QDC and 1 TDC)Simplified data selection
Reactor power
Reactor power
Rate of neutrino-like events detected per day
Rate of neutrino-like events detected per day
Time [hours]
S/B1
DANSSino results: it works! 100 /day S/B 1 E-resolution is poorer than expected:
n = 10 ph.e./MeV
2.5 MeV 25 ph.e. 25 20%
How to improve Energy Resolution?
The signal should be increased (light yield + light collection + quantum efficiency)
arXiv:1305.3350 [physics.ins-det] arXiv:1304.3696 [physics.ins-det]
17
… if the after ends of strips be UV-illuminated, one can see:
2500 strips of Kharkov (UA) scintillator have been already prepared (equipped with WLS-fibers and MPPCs). But…
17161310
1012
Visible only before the fibers been glued in!
Improvements implemented:
• All prepared strips have been thrown away and new 2500 strips have been selected (by color) from 7000
• Ultra Bialkali PMT R7600U-200 replaced by Extended Green Bialkali ones R7600U-300
• Home-made MPPC replaced by Hamamatsu S12825-050C(X) – new! with reduced noise
19
22
Hamamatsu MPPCS12825-050C(X)
18 + 22 = 40 p.e./MeV
Resolution @ E=4 MeV:
N =(4.01.8)×40 = 88 p.e.
E/E = √N / N = 11% ()
= 25% (FWHM)0 5 10 15 20 25 30
0
5
10
15
0 5 10 15 20 25 300
5
10
15
0 5 10 15 20 25 300
5
10
15
0 5 10 15 20 25 300
5
10
15
Hamamatsu PMTR7600U-200 #0214
Hamamatsu PMTR7600U-200 #0213
Hamamatsu PMTR7600U-200 #0212
Hamamatsu PMT R7600U-300 #0092
p.e./ MeV
Number of strips
18
DANSSino DANSSino2Huge edge effects
efficiency 10-15%
(instead of 72)
~400 IBD/day(S/B >> 1)
5 MPPC 1.3 x 1.3
1 MPPC 3.0 x 3.0
5 DANSS strips (shortcut)
1 ENVINET plate
PMT
PMT
13.2 pe/MeV
19.7 pe/MeV
Optimization of the basic scintillator element (ENVINET plate)
• WLS fibers: Kuraray (JP) vs Bicron (St-Gobain) vs
• pTP concentration: 0.6 – 1.0 – 1.5 – 2.0 – 2.5 – 3.0 – 3.5 %
• POPOP concentration: 1/10 – 1/5 – 1/2 – 1/1 – 2/1 of standard
• Wrapping: Mylar – Teflon – Tyvek – BC620 - …
• MPPC: Hamamatsu vs SensL
V = 4*4*4 = 64 L4 * 10 = 40 X-plates (1*20*40 cm)4 * 10 = 40 X-plates (1*20*40 cm)
8 PMT + 200 MPPC 8 PMT + 80 MPPC
X
Y
DANSSino2 S3
40 p.e./MeV
70-80 p.e./MeV
~400 IBD/daytomography?..
Temelin NPP@CZ: 2 x ВВЭР-1000
Due date
• Final mounting of the lifting system: Sep 2014• Mounting of the moveable platform: Oct 2014• Mounting of the bottom shielding: Nov 2014• New control board of the lifting system: Feb 2015 • Mounting of the DANSS detector: Mar 2015• Mounting and tuning of the ACQ: summer 2015• Mounting of the rest shielding: summer 2015• Mounting of the Muon Veto: summer 2015• Start of data taking: summer 2015• Off-line and on-line tests with S3 summer 2015
@(KNPP and Temelin NPP)
The main braking factor: mnt. could be performed
only when the reactor is stopped for recharge…
ITEP (Moscow)
CTU (Prague)JINR part of the
DANSS team
Few words about
“sterile sensitivity”of DANSS 1y operation
9 10 11 120,82
0,84
0,86
0,88
0,90
0,92
0,94
0,96
0,98
1,00
L [m]
SF / SZ
6.00 ± 0.48 MeV
Middleposition
Bottomposition
Topposition
5.00 ± 0.44 MeV
4.00 ± 0.40 MeV3.00 ± 0.36 MeV
2.00 ± 0.28 MeV
Core dim. : D3.12 x H3.50 mBurning prob. : p~cos(h/H)cos(r/D)E resolution : 25 p.e./MeV
All parameters of the reactor
and the detector are known absolutely
Optimistic caseWe compare (at 90%CL) absolute count rates in 3 positions (100 days/pos) withcalculated ones - keV by keV
Absolute neutrino
intensity and the detector efficiency are not known
Realistic caseWe compare (at 90%CL) shapes of energy spectra in 3 positions (100 days/pos) withcalculated ones - keV by keV
Only geometric
parameters of the reactor
and the detector are known
Pessimistic caseWe compare (at 90%CL) evolution of each energy bin with distance (3 positions, 100 days/pos)
Theor. E-spectra,fuel composition,power variations,detector efficiencyare not used at all.
Ongoing projects with reactor short-range neutrino oscillations
name scintil. mass segm. depth mov. Dist MW Status
DANSS @ RU SS + Gd 1.0 2500 50 + 9.7 – 12.2 3000 mount
Nucifer @ FR LS + Gd 0.75 1 13 – 7 70 operation
Neutrino4 @ RU LS + Gd 2.2 2 few + 6-12 100 mount
STEREO @ FR LS + Gd 1.75 1 18 + 8.8 – 11.2 50 R&D
SoLid @ UK 6LiF:ZnS 3.0 64 10 – 6 – 8 45 – 80 R&D
(Hanaro) @ KR LS + Gd,6Li 0.5 1 few + 6 30 R&D
PROSPECT @ US LS + Gd,6Li 1 & 10 1 few – 4 & 18 20 – 120 R&D
NuLat @ US SS + 10B,6Li 1.0 3375 few + 3 – 8 1500 R&D
Poseidon @ RU LS + Gd 1.5 5 few – 5 – 15 100 MC
(CARR) @ CN LS + Gd ~1 1 few – 7 & 15 60 MC
Happy end
e e
e
Spare slides
Detection idea: Inverse Beta-Decayin plastic scintillator interlayed with Gd or
Cd
e+
157Gd(n,) E=8 MeV =255000155Gd(n,) E=8 MeV = 60900
≈ 2-30 s
X1
X2
X3
X4
X5
Y1 Y2 Y3 Y4 Y5
ORAny X
ORAny Y
ANDNeutron
Section #3
Probably,IBD happened
@(X=2,Y=2,Z=3)↓
read detailed info from all X- and Y-strips around the event position (within 50 μs before the trigger) and check if there was a positron.
Section #3
X1
X2
X3
X4
X5
Y1 Y2 Y3 Y4 Y5
ORAny X
ORAny Y
ANDNeutron
E > 2
E > 2
(n,)
Calibration system
25 X + 25 Y capillaries run through the entire detector body (at the axis of each of 50 modules)
Radioactive source:
137Cs (, e)22Na (, e+)
60Co ()248Cm (,3n,)
etc.
Teflon tube
The role of the source dimensions
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30
0.83
0.84
0.85
0.86
0.87
0.88
0.89
0.90
0.91
0.92
0.93
0.94
0.95
0.96
0.97
0.98
0.99
1.00
Ep = 3.5-4.5 M eV
Reactor - Detector distance [m ]
Point-like reactor
Flat-burning reactor
Real reactor ВВЭР-1000 (h=3.50 m d=3.12 m)
0 5 10 15 20 25 30 35
2
3
4
56789
2
3
4
56
1
10
True IBD
Random -n
-induced
248Cm
Time, μs
Relative number of events
Spectrum simulated for
235U fission
Rate of neutrino-like events / 0.5 MeV / day(Differential spectrum = ON — OFF)
PromptEnergy
MeV
C1
C2
detector
fibers&
QDC
PMT
PMT-1
PMT-2
gate
signaldelay
UV LED
0 50 100 150 200 2500
100
200
300
k=0
k=1k=2,3,...
QDC-chn0 1000 2000 3000 4000 5000 6000 7000
0,1
0,2
0,3
0,4
Max=1.77
Med=1.93
Mean=2.09
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