11

GEMMA:GEMMA: experimental searches for experimental searches for

neutrino magnetic moment neutrino magnetic moment

JINR:JINR: V. Brudanin, V.V. Brudanin, V.  Egorov, D. Medvedev, M. ShirchenkoEgorov, D. Medvedev, M. Shirchenko, ,

E. Shevchik, I. Zhitnikov, V. BelovE. Shevchik, I. Zhitnikov, V. Belov

ITEP:ITEP: A. Beda, A.A. Beda, A.  StarostinStarostin

22

Scientific motivationScientific motivation

Minimally extended Standard ModelMinimally extended Standard Model ( (MSM)MSM): :

~ ~ 1010––1919 BB (m (m / 1eV) / 1eV)

νL νR

l

W

γ

νL νRl

Wγ

33

Scientific motivationScientific motivation

Beyond theBeyond the MSM: MSM:

≤≤ 1010––1414 BB (m (m / 1eV) / 1eV)

~ ~ 1010––1010 - 10 - 10––1111 BB

44

Matrix of magnetic momentMatrix of magnetic moment

e

e

eeee

55

Calculation ofCalculation of ΛΛ parameterparameter

[[]] 4*10 4*10-9-9BB ([m ([m]]/1eV)* /1eV)*

(1TeV/(1TeV/))22 * *mm22/(m/(m

22-m-m22))

Bell N. F. How magnetic is the neutrino? // WSPC Proceedings; hep-ph/0707.1556.Bell N. F. How magnetic is the neutrino? // WSPC Proceedings; hep-ph/0707.1556.

ForFor =10=10-11-11 BB andand mm=0.3 eV=0.3 eV

ΛΛ<100 TeV<100 TeV

66

Observation ofObservation of ~~1100-11-11-1-100--1212 BB willwill:: give a hint of neutrino naturegive a hint of neutrino nature aallow to feel the scale ofllow to feel the scale of ΛΛ sset the restrictions on the number of et the restrictions on the number of

astrophysical models astrophysical models

Scientific motivation (summary)Scientific motivation (summary)

77

Direct searches for Direct searches for Reactor neutrinos: Reactor neutrinos:

– MUNUMUNU, , TEXONOTEXONO, , GEMMAGEMMA <(2.9 – 9)*10<(2.9 – 9)*10-11 -11 BB (e) (e)

Solar neutrinos:Solar neutrinos:– SK+KamLandSK+KamLand, , BorexinoBorexino

<(5.4 – 11)*10<(5.4 – 11)*10-11-11 BB (all) (all)

Accelerator neutrinos:Accelerator neutrinos:– LSNDLSND, , DONUTDONUT

<1.1*10<1.1*10-9-9 BB (e) (e) <6.8*10<6.8*10-10-10 BB ( ()) <3.7*10<3.7*10-7-7 BB ( (ττ))

8

Upper limits on

μν upper limit Comments

Solar <4*10-10

SK+KamLand <1.1*10-10

White dwarfs <10-11

model dependentRed giants <3*10-12

Supernova 1987A <3*10-12

“Cosmological” limit

<1.5*10-11 should not be violated by more than two neutrino species

BOREXINO <5.4*10-11

TEXONO <7.2*10-11

MUNU <9*10-11

99

First reactor experimentsFirst reactor experiments1976 – Savannah River. 1976 – Savannah River. The first observation of the The first observation of the -e-e

scattering scattering F. Reines et al. F. Reines et al. [P.R.L.37,315(1976)].[P.R.L.37,315(1976)]. ~ 16 kg plastic scintillator, ~ 16 kg plastic scintillator, flux of 2.2×10 flux of 2.2×101313 / cm / cm 22 / s / s1989 – 1989 – A revised analysis by P. Vogel and J. EngelA revised analysis by P. Vogel and J. Engel

[P.R.,D39,3378(1989[P.R.,D39,3378(1989)])] gave a limit gave a limit

( 2 – 4) ( 2 – 4) 10 10 –10–10 BB

1992 – Krasnoyarsk.1992 – Krasnoyarsk. G.S. Vidykin et al. G.S. Vidykin et al. [Pis’ma v ZhETPh,[Pis’ma v ZhETPh, 55,206(1992)]55,206(1992)]

~ 100 kg liquid scintillator C~ 100 kg liquid scintillator C66FF66, 254 days “on” / 78 days “off “, 254 days “on” / 78 days “off “

2.4 2.4 10 10 ––1010 BB (90% C.L.) (90% C.L.) 1993 – Rovno.1993 – Rovno. A.V. Derbin, L.A. Popeko et al. A.V. Derbin, L.A. Popeko et al. [JETP Letters,[JETP Letters,

57,768(1993)]57,768(1993)] 75 kg silicon multi-detector, 600 Si(Li) cells, 75 kg silicon multi-detector, 600 Si(Li) cells,

--flux of ~ 2×10flux of ~ 2×101313 / cm / cm 22 / s / s , 30 days “on”/17 days “off “ , 30 days “on”/17 days “off “

11 .9 .9 10 10 –10–10 BB (95% C.L.) (95% C.L.)

1010

measurement under reactormeasurement under reactor

The effects can be searched in the recoil The effects can be searched in the recoil electron energy spectrum from the electron energy spectrum from the

- e- e scattering scattering measured when the reactor is measured when the reactor is ONON and and

OFFOFF..

The total cross-section dThe total cross-section d/dT is a sum of /dT is a sum of

two: two: ( d( d/dT )/dT )weak weak + + ( d( d/dT )/dT )EMEM

depending on the recoil energy depending on the recoil energy TT in different in different waysways

1 10 100

1 10

23 4 5

T [keV]

d / dT

6 10

W

d / dT ( )EM

10

100

1000

-11

-11

d / dT [10 cm / MeV / fission / electron ]45 2

1212

Reactor unit #2 of the

“Kalinin” Nuclear Power Plant

(400 km North from Moscow)

Technological roomjust under reactor

14 m14 m only!2.71013 /cm2/s

Power: 3 GWON: 315315 days/yOFF: 5050 days/y

Total mass above(reactor, building, shielding, etc.):

~70 m~70 m of W.E.

1313

Experiment Experiment GEMMAGEMMA

((GGermanium ermanium EExperiment xperiment for measurement of for measurement of MMagnetic agnetic MMoment of oment of

AAntineutrinontineutrino))

[[Phys. of At. Nucl.,Phys. of At. Nucl.,6767(2004)1948(2004)1948]]

Spectrometer includes a Spectrometer includes a HPGeHPGe detector of detector of 1.5 kg1.5 kg installed within installed within NaINaI active active shielding. shielding.

HPGe + NaI are HPGe + NaI are surrounded with multi-layer surrounded with multi-layer passive shielding :passive shielding : electrolytic electrolytic coppercopper, , borated borated polyethylenepolyethylene and and leadlead..

1414

GEMMA background conditionsGEMMA background conditions -rays-rays were measu- were measu-

red with Ge detector. red with Ge detector. The main sources are:The main sources are: 137137CsCs , , 6060CoCo,, 134134CsCs..

NeutronNeutron background background was measured with was measured with 33He counters, i.e., He counters, i.e., thermal neutrons were thermal neutrons were counted.counted. Their flux at Their flux at the facility site turned the facility site turned out to beout to be 30 times 30 times lowerlower than in the than in the outside laboratory outside laboratory room.room.

ChargedCharged component component of the cosmic radiation of the cosmic radiation ((muonsmuons) was measu-) was measu-red to bered to be 5 times 5 times lowerlower than outside.than outside.

1515

Background suppresionBackground suppresion

1616

Background at low energy regionBackground at low energy region

1717

EnergyADCAmp. Gedetector

ADC-1

ADC-2

E1

E2

1

2

High freq. noise: E1 > E2

Real signal: E1 = E2

Low freq. noise: E1 < E2

E.Garcia e.a. NPB28A(1992)286

1818

0

5

10

15

20

25

0 5 10 15 20 25 30

ADC-1 [keV]

ADC-3 [keV]

19

Spectrum after “matrix applying”Spectrum before “matrix applying”

keV

2020

0 100 200 300 40010000

100000

1000000

dT [ms]

true eventsmicrophonics

mains freq. (50 Hz)

Time selection of consecutive events:

2121

22

Final spectra

23

Final distribution

-30.0 -20.0 -10.0 0.0 10.0 20.0 30.0

X = 8.37 (90% CL)

Probability distribution[a.u.]

C.L.

X

X = -5.790

Non-physicalregion ( X< 0 )

0

10

20

30

40

50

60

70

80

90

100

Re-normalized area

2424

Experimental sensitivityExperimental sensitivityNN : number of signal events expected

BB : background level in the ROI

mm : target (=detector) mass

tt : measurement time

NN ~~ ( ~ ( ~ PowerPower // rr 22 ) )

~~ (( TTmaxmax- - TTminmin / / TTmaxmax**TTminmin ))1/21/2

GEMMA I GEMMA I ~~ 2.7 ×1013 / cm2 / s

t ~ 4 years

B ~ 2.5 keV-1 kg-1 day-1

m ~ 1.5 kg Tth ~ 2.8 keV

2.9 10 –11 B

4

1

1

mt

BN

2525

Data SetData Set I phase I phase – 5184 – 5184 hh ON, ON, 1853 1853 hh OFFOFF

II phaseII phase – 6798 – 6798 hh ON, ON, 1021 1021 hh OFFOFF I+III+II – 11982 – 11982 hh ON, ON, 2874 2874 hh OFFOFF

III phaseIII phase – 6152 – 6152 h h ON, 1ON, 1613613 h h OFFOFF I+II+IIII+II+III – 18134 – 18134 hh ON, 4487ON, 4487 hh OFFOFF

B1110*8.5

B1110*2.3

B1110*9.2

Beda A.G. et al. // Advances in High Energy Physics. 2012. V. 2012, Article ID 350150.Beda A.G. et al. // Physics of Particles and Nuclei Letters, 2013, V. 10, №2, pp. 139–143.

2626

#2: 14 m

#3: 10 m

KNPPKNPP

UdomlyaUdomlya

RussiaRussia

2727

GEMMA IIGEMMA II

~~ 55×10×101313 / cm / cm22 / s / s tt ~~ 2 years 2 years BB ~ 0.5–1.0 keV ~ 0.5–1.0 keV -1-1kg kg -1-1dayday-1-1

mm ~ 6 kg (~ 6 kg (two detectorstwo detectors)) TTthth ~ 1.5 keV~ 1.5 keV

1.0 10 -11 B

2828

Lifting mechanism

GEMMA-II

3030

Future detectorsFuture detectors

3131

Calibration spectrum in Dubna with (Fe-55, Al) sourceAchieved energy threshold is ~350 eV

32

0,0 0,2 0,4 0,6 0,8 1,0 1,2 1,4 1,6 1,8 2,0 2,2 2,4 2,6 2,8 3,01,4

1,6

1,8

2,0

2,2

2,4

2,6

2,8

3,0se

nsi

tivity

to

,

10

-11

B

E(threshold), keV

Changing Background Constant Background

33

Sensitivity of future experiments

B = 0.2 1/keV/kg/day

Mass, kg Threshold, keV Sensitivity, 10-12μB

4.5 0.4 5.8

10 0.4 4.7

20 0.4 4.0

4.5 0.3 5.6

10 0.3 4.6

20 0.3 3.9