Highly intensive antineutrino tritium source:
Specifics of physical experiment.
Russian Federal Nuclear Center – All-Russian Scientific –ResearchInstitute for Experimental Physic
Sarov, Nizhniy Novgorod reg., Russia
Yukhimchuk Arkadiyarkad@triton.vniief.ru, +7 8313023473

Intensive Antineutrino Tritium Source (ATS) [1,2] for neutrino
magnetic moment experiment
Advantages of the tritium
antineutrino source•••••

More intensive antineutrino flows ascompared with the reactor and accelerator
sources;
Strongly suppressed correlated
background;
Small sizes allowing using low-backgroundunderground laboratories and flow
modulation for the non-correlated
background deduction;
Knowledge of the antineutrino spectrumwith high precision;
Low boundary energy of the decay
spectrum (Е0 = 18.6 keV) – thebremsstrahlung radiation doesn’t gobeyond the limits of the source, there is nonecessity in the passive protection between
the source and detector.

For the reactor with the power of 1 GW suchflow may be obtained in the detector at thedistance of 10 m from the reactor core.

The maximum flow along
the detector axis is6·1014 cm-2·s-1

1. V.N. Trofimov, B.S. Neganov, A.A. Yukhimchuk. Measurement of the neutrino magnetic moment at a level better than 10 -12 B with atritium  -emitter and cryodetector (project). Physics of atomic nuclei.1998. Т.61. No.8. p.1271-1273.
2. B.S. Neganov, et al. Status of the experiment on the laboratory search for the electron antineutrino magnetic moment at the level3·10-12B. Physics of atomic nuclei. 2001. Т.64. №11. p.2033-2039.

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The First ATS Design for Measuring the Neutrino Magnetic Momentum

0.328 W/g; 1.954 W/mole
In order to reach the maximum density of the (anti)neutrino flow, it is necessary to provide themaximum bulk tritium activity in the structure of the source. Also, such source should be
absolutely safe in all, including extreme, circumstances. The most suitable for that is tritium
storage in the chemically bound condition using hydride-forming metals, which on the on hand
have a higher bulk density of the hydrogen contents, and on the other hand tritium there has low
equilibrium pressures at the room temperatures.
Titanium dehydrate is chosen. There is a low equilibrium pressure. The bulk content of tritium per
Ti is practically 1.7 times higher than in case of tritium in the liquid state. There is the opportunityof safe operation at up to 500°С, while in order to keep tritium in the liquid state, it is required
quite a powerful refrigerating facility allowing sustaining the tritium temperature at about 20K(with account for its heat release).

The ATS heat calculation in the conditions of
natural storage showed its considerable heating. In
the center of the source the temperature exceeded309°С that caused certain difficulties in the courseof transportation, storage and operation of such
source. Besides, its manufacturing would require aspecial process facility.

3The Evolution of Views on the ATS Design
We have performed the works aimed at the ATS design
optimization [3, 4]. In doing so, the following factors weretaken into account:• Having the available tritium amount, we aimed at
obtaining the maximum number of the events ofneutrino interaction with the detector material;• Detector sizers and shape;• Technological capabilities of manufacturing the source
structural elements;• Possibility of obtaining titanium tritide (TiT) of the ДетекторDetector
necessary density;• Behavior during the operation;• Safety at all the ATS operation lifecycle stages;• Convenience of mounting and dismounting.

CylinderЦилиндрa)SphereСфераСоставная
TTEконструкция
assemblyиз ТЭЛовb)ИсточникSource

3. Yu.I. Vinogradov et al. Optimization of the tritium source design for the experimental facility. In the collected papers “Hydrogenisotopes and applied research” edited by A.A. Yukhimchuk, FSUE “RFNC-VNIIEF”, 2009, P.212-221.
4. A.A. Yukhimchuk et al. Status of works a 40-MCi-activity source for the measurement of the antineutrino magnetic moment. Fusion
Science and Technology, 48 (2005) 731-736.
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The Results of Optimization9 =3.5 g/cm

8347
2
1R1R2R3R414X1F(R,Z), 10 cm s-2 -1

3X4X2X36543

 =1.75 g/cm

M =37.7 kg

3

R = 0 cm

2The source design includes 80
copper tubular elements withtitanium tritide.

R = 1 cm
R = 3 cm

10-15-10-5051015Z, cm

The neutrino flow density is½ ModelF  61014cm-2  s-1 along the axis Z of thedetector
5Previous Projects Aimed at Defining the in-Lab Lower Limit of Neutrino MagneticMomentum  ~ 10-12 B with the ATS with the Activity of 40 MCi
The project “Mammoth”
 ITNS – the flow density: 61014 cm-2s-1 (RFNC-VNIIEF)
 Detectors with the ultra-low threshold Eth~10 eV:

 Silicon cryodetectors (T=10 mK) 15100cm3, M=3kg, the effect of the ionizationtransformation into heat (JINR-CWRU-Stanford)
HPGe detectors 6150cm3, M=4.8 kg, the internal proportional amplification of the signal(the avalanche amplification) in the electric field (ITEP)

The project of the SRC “Kurchatov Institute” and RFNC-VNIIEF• The effect of neutrino scattering at electrons of liquid helium atoms → excitation →relaxation of helium atoms with emitting a photon in the ultraviolet part of the spectrum→ conversion of the ultraviolet spectrum into the visual one → recording of the photons
using a photoelectronic multiplier [5]5. V.P. Martemyanov, et al. Probing of the Neutrino Magnetic Moment at the Levev of10-12 µB with an Intense Tritium Source of (Anti)Neutrino and Helium Target (Project).
Fusion Science and Technology, V.67, N.2&3 (2015) 535-538.

Technical, technological and organizational issues of the ITNS development (of any intensity) were resolved.
The questions connected with using the ITNS with respect to particular conditions may appear.
The projects were not implemented because of the problems connected with the development of the necessary
detection systems.

6Tritium Experiment Specifics
Tritium properties
Half-decay constant, Т1/2, yearsТ1/2, days
Decay energy, max., keV
average, keV
Decay heat release
Specific radioactivity Т2 (gas)12.232 ± 0.004 (1 год=365.25 days)
4500.88 ± 1.46
18.5825.685
0.328 W/g; 1.954 W/mole
355.9 TBq/g (9.619 kCi/g)
2146.9 TBq/mole (58.023 kCi/mole)
2.589 Ci/сm3=0.386 сm3/Ci (at n.c.)
2.372 Ci/сm3=0.422 сm3/Ci (at n.c.)

Density Т2 (gas) at n.c., 103 g/сm3
Run of β – particles in the air (n.c.), сm
Т2 (has, n.c.), сmwater (dry material, oil, polymers at
ρ=1 g/сm3), mcm
steel, mcm

0.269122
0.036 (5.7 keV); 0.45 (18.6 keV)
0.26 (5.7 keV); 3.2 (18.6 keV)
0.42 (5.7 keV); 5. 2 (18.6 keV)
0.06 (5.7 keV)

Organization of the works: licensing,arrangement ofsites and premises, requirements to the equipment,ventilation, water supply and sewage, arrangement of theradiation control etc. However, with respect to theexperimental facilities and complexes, fulfilment of all theserequirements to the full extent is not possible, and thedevelopment of new approaches and technical decisions isrequired, in order to create the radiation-safe equipment fortritium operations at existing physical facilities along withobserving the RF regulatory base.
Approach: development of devices containing tritium or its
compounds classified as covered radioactive sources
According to NRB 99/2009, “A covered radioactive source is adevice, the design of which excludes the excursion ofradionuclides contained therein into the environment underconditions of the application and wear, which it is calculatedfor”.

7Recent Proposal [6] ~ 4,1x10-13 B : 500 g T2
The response of a helium atom afterscattering at it of an electronic
antineutrino from the tritium source inthe center leads to the excitation ofphonons and rotons, which uponreaching the upper surface cause thequantum evaporation of helium atoms(i.e. their cutting off from the surface asa result of the phonon or roton
absorption). With the help of thedetector matrix (using the method of thefiled ionization) mounted above theupper surface the amount of theevaporated helium atoms is determined.

1-4 kgT2 :  ~ ???? B
6. M. Cadeddu, F. Dordei, C. Giunti, K.A. Kouzakov, E. Picciau, and A.I. Studenikin et al. Potentialities of a low-energy detector
based on 4He evaporation to observe atomic effects in coherent neutrino scattering and physics perspectives.
Phys. Rev D 100, 073014 (2019) .
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The Project within the Framework of the National Physics and Mathematics
Center (Sarov). Measurement of neutrino electromagnetic properties using
ITNS
The project is prepared jointly with the MGU scientific group for neutrino physics
led by Professor A.I. Studenikin.

Proposed:
ATS with the activity of up to 40 MCi (4 kg of tritium). At the first stage it isconsidered the source with ~ 10 MCi (1 kg).
Detector – liquid helium in a super-fluid condition (the temperature is ~0.1К),neutrino scattering at helium atoms, recording of the quantum helium
evaporation from the liquid surface, using the field ionization method.
Other detector types are considered!!!

Low-background laboratory for suppression of harsh cosmic radiation.
According to evaluations, ~ 6-10 m of concrete are sufficient.
Available: 0.5 m of concrete, 5 m of sand, 7 m of the ground. ?? Is it enough??
Collaboration: VNIIEF, MGU, PA “Mayak”, JINR, SRC “Kurchatov
Institute” ……is open for participation!!!

432
1The detector-source structural diagram:1 – tritium at titanium, 2 – liquid helium 0.1 К,
3 – thermal protection, 4 – detector matrix (thefield ionization method).

Other detector types arewelcome!!!
Other ideas of using theATS are welcome!!!

You are invited to the mutually beneficial collaboration!
9Thank you foryour attention

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