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