ννGEMMAGEMMA

search for the search for the

Neutrino Magnetic Neutrino Magnetic MomentMoment

JINR DubnaJINR Dubna

ITEP MoscowITEP Moscow

V.Egorov

Science motivation of the searching for Science motivation of the searching for μμ

• minimally-extended Standard Model: minimally-extended Standard Model:

~ 10–19 B (m / 1eV)

≡ 0

Bohr magneton B

= eh / 2 me

Science motivation of the searching for Science motivation of the searching for μμ

• number of extensions beyond the MSM:number of extensions beyond the MSM:

≤ 10–14 B (m / 1eV)

~ 10–10 - 10–11 B

• Observation of (Observation of (~10–12) => D/M ) => D/M preferencepreference

Bohr magneton B

= eh / 2 me

Limits for the NMM from Limits for the NMM from astrophysicsastrophysics

(model dependent !!!)(model dependent !!!) The neutrino interactions are very important for stars evolution in The neutrino interactions are very important for stars evolution in

their late stage (90% of energy emission in old stars is done by their late stage (90% of energy emission in old stars is done by neutrinos)neutrinos)

• He starHe star (0.1 – 0.03) (0.1 – 0.03) 1010––1010 BB core mass at the flashcore mass at the flash

• White dwarfWhite dwarf (0.4 – 0.05) (0.4 – 0.05) 1010––1010 BB luminosity functionluminosity function

• SN 1987 ASN 1987 A (0.4 – 0.05) (0.4 – 0.05) 10 10––1010 BB EE in neutrino burst in neutrino burst

The model dependence: The model dependence:

…… …… a slight decrease in temperature leads to significant suppression a slight decrease in temperature leads to significant suppression in neutrino emission….in neutrino emission…. (M. Fukugita) (M. Fukugita)

…… …… SN 1987 limits apply only for Dirac neutrino ……SN 1987 limits apply only for Dirac neutrino ……

Limits for the NMM from solar Limits for the NMM from solar datadata• Resonance and non-resonance spin – flavor precession in Resonance and non-resonance spin – flavor precession in solar magnetic field can excite distortion of neutrino solar magnetic field can excite distortion of neutrino spectra.spectra.

• The spectrum distortion analysis of SK and BOREXINO The spectrum distortion analysis of SK and BOREXINO electron recoil spectrum can allow to set limit for electron recoil spectrum can allow to set limit for ::

1.1 1.1 1010––1010BB (90% CL)(90% CL) – – SK + constrains from the other solar SK + constrains from the other solar

neutrino and KamLAND results.neutrino and KamLAND results.

5.4 5.4 1010––1111BB (90% CL)(90% CL) – – BOREXINO dataBOREXINO data There are bounds on Majorana neutrino transition momentsThere are bounds on Majorana neutrino transition moments obtained both from obtained both from …… ……solar neutrino data alone solar neutrino data alone ((J.F. Beacom, P. Vogel)J.F. Beacom, P. Vogel) … …..and using solar neutrino data combined with the results ..and using solar neutrino data combined with the results of the reactor experiments of the reactor experiments ((W. Grimus at al.)W. Grimus at al.)

Limits for the NMM from Limits for the NMM from astrophysicsastrophysics

(model dependent !!!)(model dependent !!!)

Reactor measurements of the Reactor measurements of the NMMNMM

• The effects of the NMM can be searched for in The effects of the NMM can be searched for in the recoil electron energy spectrum from the the recoil electron energy spectrum from the

- e- e scattering scattering measured with the reactor measured with the reactor ONON and and OFFOFF..

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

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

depending on the recoil energy depending on the recoil energy TT in a very in a very different waydifferent way

Limits for the NMM from Limits for the NMM from astrophysicsastrophysics

(model dependent !!!)(model dependent !!!)Limits for the NMM from solar Limits for the NMM from solar datadata

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

The 30y history of the reactor The 30y history of the reactor experimentsexperiments

1976 – Savannah River. 1976 – Savannah River. The first observation of the - e scattering. F. Reines et al. [P.R.L.37,315(1976)]. ~ 16 kg plastic scintillator, flux of 2.2×10 13 / cm 2 / s1989 – – A revised analysis by P. Vogel and J. Engel [P.R.,D39,3378(1989)]:

( 2 – 4) 10 –10 B

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

~ 100 kg liquid scintillator C6F6, 254 days “on” / 78 days “off “

2.4 10 –10 B (90% CL) 1993 – – Rovno. A.V. Derbin, L.A. Popeko et al. [JETP Letters, 57,768(1993)] 75 kg silicon multi-detector, 600 Si(Li) cells, -flux of ~ 2×10 13 / cm 2 / s , 30 days “on”/17 days “off “

1 .9 10 –10 B (95% CL)

The 30y history of the reactor The 30y history of the reactor experimentsexperiments

2001-2005 – Bugey. 2001-2005 – Bugey. The MUNU experiment.The MUNU experiment. Z. Darakchieva et al. [P.L.B. 615 (2005)]. ~ 11.4 kg CF4 TPC, 66.6 days “on” / 16.7 days “off “

9 10 –11 B

1989 – Moscow. Proposed to detect (1989 – Moscow. Proposed to detect (νν– – e e ) scattering ) scattering with low-background HPGe. A.Vasenko et al. [P.T.E.(rus), 2,56(1989)]A.Vasenko et al. [P.T.E.(rus), 2,56(1989)]

2001- … – Taiwan2001- … – Taiwan.. The TEXONO experimentThe TEXONO experiment H.T.Wong et al. [P.R. D75 (2007)]

1 kg HPGe detector, -flux of ~ 6.4×10 12 / cm 2 / s 570 days “on” / 127 days “off “

7.4 10 –11 B (90% CL)

2005- … – Udomlya – Udomlya. The GEMMA experimentThe GEMMA experiment A.Beda et al. [P.A.N. (rus), 70(2007)]

1.5 kg HPGe detector, -flux of ~ 2.7×10 13 / cm 2 / s , 216 days “on”/ 77 days “off “

5 .8 10 –11 B (90% CL)

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.

Phase-1: 13 months (08.2005-09.2006) = 216 days ON + 77 days OFF

Phase-2: 19 months (09.2006-05.2008) = 283 days ON + 42 days OFF

Phase-3: 18 months (05.2008-11.2009) ─ data analysis is in progress…

Experiment Experiment GEMMA1GEMMA1

((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..

GEMMA background GEMMA background conditionsconditions -rays were measu-

red with Ge detector. The main sources are: 137Cs , 60Co, 134Cs.

• Neutron background was measured with 3He counters, i.e., thermal neutrons were counted. Their flux at the facility site turned out to be 30 times lower than in the outside laboratory room.

• Charged component of the cosmic radiation (muons) was measu-red to be 5 times lower than outside.

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

0

5

10

15

20

25

0 5 10 15 20 25 30

ADC-1 [keV]

ADC-3 [keV]

0 100 200 300 40010000

100000

1000000

dT [ms]

true eventsmicrophonics

mains freq. (50 Hz)

Time selection of consecutive events:

0 5 10 15 20 25 30 35 40 45 50 55 60 65 701

10

100

1000

Energy [keV]

Counts / 0.1 keV / 1000 hr

0 5 10 15 20 25 30 35 40 45 50 55 60 65 701

10

100

1000

Energy [keV]

0 5 10 15 20 25 30 35 40 45 50 55 60 65 70

-100

-50

0

50

100

Energy [keV]

(On - Off - W eak)ElectroMagnetic

O f f

O n

Phase- I I

Counts / 0.1 keV / 1000 hr

ON = norm ON = norm · · [[OFF + W + OFF + W +

X·EMX·EM]]

Spectrum measured with

the reactor being in

operation

Spectrum measured with

the reactor being shut

downWeak

contribution

ElectroMagnetic cross-section

Normalization factor =

= T(ON) / T(OFF)

Amplitude of the EM-contribution =

= (μ / 10–11 μB)2

(Free parameters)

Renormalized part

3.2×10–11 μB

When the wavelength of the virtual photon *

becomes comparable to an atomic size

(i.e., at T< 10 keV),it can interact with the atom as a whole and cause photoelectric

effect

expected

GEMMA NME limits (Phases GEMMA NME limits (Phases 1+2)1+2)

NMM interaction taken into accountNMM interaction taken into account FEFE FE+AIFE+AI

3.2 × 103.2 × 10–11–11 μμBB 5.0 × 105.0 × 10–12–12 μμBB

mainly mainly SYSTEMATICSYSTEMATIC

The low energy region is The low energy region is much more important much more important

than even was than even was expected…expected…

We are close to a principle We are close to a principle limitation of the existing limitation of the existing

apparatusapparatus

need to upgradeneed to upgradeGEMMA-1 GEMMA-1 → GEMMA-→ GEMMA-

22

Change the detector (1.5 kg → 6 kg)

and the cryostat (std → low bckg)U-type

cryostat23 kg HPGe

detectors

Lifting mechanism

GEMMA-2

#2: 14 m

#3: 10 m

KNPPKNPP

UdomlyaUdomlya

RussiaRussia

HPGe: HPGe: 1.5 kg 1.5 kg 6 kg 6 kgE-threshold:E-threshold: 3.0 3.0 1.5 keV 1.5 keVCryostat: Cryostat: std std U-type U-typeReactor unit: Reactor unit: #2 #2 #3 #3Distance: Distance: 14 m 14 m 10 m 10 m (movable)(movable)-flux: -flux: 2.7 2.7 5.0 5.0 ×10×101313

Upgrade 2010’: Upgrade 2010’: GEMMA-2GEMMA-2

Future Future perspectivesperspectives

Ge detectors with very low Ge detectors with very low thresholdthreshold ((~ 3~ 300 00 eVeV))RFBR grantRFBR grant

h = 25 mm

d = 65 mm

m = 460 g