Project of ultracold neutron source with superfluid helium at WWR-M reactor (PNPI, Gatchina) and scientific research program А.P.

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1 Project of ultracold neutron source with superfluid helium at WWR-M reactor (PNPI, Gatchina) and scientific research program А.P. Serebrov UCN2010 International Workshop on UCN and Fundamental Neutron Physics RCNP, Japan April 8-9,

2 Content 1. UCN sources at PNPI 2. Ultracold neutron source with superfluid helium 3. New facilities of WWR-M reactor 4. Scientific research program 5. Movie How it will be 2

3 UCN sources produced by PNPI

4 Conceptual idea of UCN source at WWR-M reactor Ф(30К)=10 12 n cm -2 s -1 Reactor core ρ ucn =10 4 n cm -3 (?) W 10 W (?) Superconductive solenoid 5T UCN UCN shutter membrane 4

5 Project of ultracold and cold neutron source with superfluid helium at WWR-M reactor 5

Neutron scattering in liquid helium I.Ya.

degree in fluid Helium II The scattering of slow neutron in He-II is

It is shown that the scattering is a negligible small at the

6 Neutron scattering in liquid helium I.Ya. Pomeranchuk Selected works About neutron scattering with energy a few degree in fluid Helium II The scattering of slow neutron in He-II is considered. It is shown that the scattering is a negligible small at the temperature below than temperature of critical point. UCN source based on superfluid He-II R. Golub, J.M. Pendlebury, Phys. Lett. A 62 (1977) 337 E beg =12 K E UCN 10-3 K λ=9 Å 6

7 Storage time of UCN in He-II (results of experiment) s 20 s 30 s s 100 s detector counts 93 s (T=0.49 K) storage time, s s T=1.16 K holding time, s 1.0 K temperature, K 1.3 K 7

8 H.Yoshiki experiment at ILL Phys. Lett. A 308 (2003) neutron count time, s neutron count storage time, s temperature, K wavelength, A UCN density in the sourceρ=сτ Ф(λ=9Å)= n/(сm 2 s А) С UCN generation (0.9±0.1) n/(сm 3 s) τ- storage time in the source ρ 10 сm -3 8

9 Thermal column of WWR-M reactor Vertical cross section of WWR-M reactor. 1 reactor core, 2 reactor tank, 3 concrete protection, 4 chamber above the reactor, 5 horizontal channel, 6 thermal column, 7 vertical channel. Cross section of WWR-M reactor 9

10 Idea UCNs are generated in helium from cold neutrons of 9Ǻ wavelength (12 K energy). It is correspond with phonon energy: cold neutron enegizes phonon, practically stops and becomes an ultracold one. UCN can lives in superfluid helium for tens or hundreds of seconds until a phonon be captured. Cold neutrons (9Ǻ) penetrate through the wall of a trap, but ultracold neutrons (500Ǻ) are reflected, that is why UCN can be accumulated up to the density defined by the time of storage in the trap filled with superfluid helium. UCNλ=500 Å, T=10-3 K CNλ=9 Å, T=12 K phonon 10

11 MCNP neutron flux calculation results and heat generation in thermal column of WWR-M reactor at 15 MW He Т=1.2 К LD 2 Т=20 К C Т=300 К Pb Т=300 К ρ ucn =10 4 сm -3 (τ=10 s) Ф= n/(сm 2 s) Ф(λ=9 А)= n/(сm 2 s) Q He =6 W Al, Q Al =13 W LD 2, Q LD2+Al =100 W 19 W C, Q C =700 W Pb, Q Pb =15 kw Ф=10 14 n/(сm 2 s) Q=15 МW 11

Cryogenic scheme of UCN source with superfluid He UCN CN 1 He II cell; 2 UCN neutron guide, 3 CN neutron guide, 4 He II supply pipe, 5 lower bath @ 1.2 К, 6 intermediate bath @ 1.

2 К, 10 helium supply valve, 11 level sensor, 12 vacuum pipe (gravitation trap for UCN), 13 vacuum pipe for lower bath, 14 vacuum pipe for intermediate bath, 15 main vacuum manifold, 16 UCN

12 Cryogenic scheme of UCN source with superfluid He UCN CN 1 He II cell; 2 UCN neutron guide, 3 CN neutron guide, 4 He II supply pipe, 5 lower 1.2 К, 6 intermediate 1.2 К, 7 3 Не filter, 8 level sensor, 9 upper 4.2 К, 10 helium supply valve, 11 level sensor, 12 vacuum pipe (gravitation trap for UCN), 13 vacuum pipe for lower bath, 14 vacuum pipe for intermediate bath, 15 main vacuum manifold, 16 UCN neutron guide membrane, 17 CN neutron guide membrane, 18 thermal 20 К, 19 vacuum jacket, 20 UCN outer neutron guide, 21 CN outer neutron guide, 22 helium supply at temperature of 4.2 К, 23 pipe for helium vapour removal, 24 helium supply for thermal shield 18, 25 helium removal from thermal shield 18, 26 pumping of vacuum jacket. 12

13 UCN density maximal density inside closed source density in experimental trap with volume 35 l density in experimental trap with volume 350 l 13

14 UCN density, cm Comparison of expected UCN density with UCN density of present sources first test experiments with superfluid He ILL [12] PNPI ILL SRIAR PNPI PNPI IAE TUM PNPI IAE JINR ILL UCN density (сm -3 ) Present project 10 4 [4] PNPI PNPI PNPI [5] first test experiment with SD 2 SD 2 pulse mode LANL-PNPI present years [8] [6] SD 2 reactor test experiment ILL [13] [3] SD 2 Mainz [9] PNPI Gain factor ILL (turbine source) PNPI project [17] PSI-PNPI projects [15-16] [10] project SD 2 in pulse mode 14

15 Cryogenic and vacuum equipment At present there are some equipment for UCN source at WWR-M reactor : Helium refrigerator TCF 50 ( К, Linde Kryotechnik AG) Helium liquefier L280 (80 l/h, Linde Kryotechnik AG ) Vacuum pump station (BOC Edwards) 15

16 Helium refrigerator 16

17 Gas management systems 17

18 Helium liquefier 18

19 Helium tank 19

20 Vacuum equipment 20

21 General view 21

22 General view 22

23 General design 23

24 Installation of UCN source on WWR-M reactor а b c d а Pb shielding mounting; b graphite block mounting; c mounting of cryostat, UCN superconductive polarizer and UCN switchboard; d mounting of biological shielding. 24

25 New facilities of WWR-M reactor 25

26 Ultracold and cold neutron source at WWR-M reactor with neutron guide halls hall of thermal neutrons hall of ultracold neutrons hall of very cold neutrons hall of cold neutrons

27 Program of fundamental research with ultracold neutrons 1. Neutron EDM and problem of CP-violation 2. Precise measurements of neutron β-decay and search for deviations from Standard Model 3. Search for neutron-antineutron oscillations 27

28 Fundamental interaction of elementary particles. Methods of research 1. High-energy physics E<10 13 ev. 2. Cosmology, astrophysics, cosmic rays, neutrino physics. 3. Precise investigations, search of small deviations to Standard law of physics. One of a way is the investigation with UCN of 10-7 ev 28

29 Problem of CP-violation and Neutron EDM 29

30 Neutron EDM and problem of CP-violation Theoretical Prediction: Neutron EDM Experimental limit (e cm) reached limit estimation of precision of PNPI project at ILL estimation of precision of PNPI project at WWR-M reactor, Gatchina MIT-BNL ORNL-Harvard ORNL-ILL... ILL-Sussex-RAL... PNPI Year - Electromagnetic - Weinberg Multi-Higgs - Minimal SUSY Cosmology - Left-Right Symm. 30

31 Neutron decay, Standard Model and Cosmology 31

32 Neutron decay and cosmology G. J. Mathews, T. Kajino, T. Shima, Phys. Rev. D 71, (R) (2005) G π ga me F ( fτn) = ( + ) τ n, world average τ n, Gravitrap result ( ) ( ) τ = 1% Y=0.75% ± 0.61% n τ = 1% η=17% ± 3.3% n New τ n =(878.5±0.8) s confirms n b /n γ from CMB.

33 Studies of the structure and dynamics of nanostructures by means of cold and very cold neutrons 33

34 Studies of the structure and dynamics of solid state

$neutrons SAPNS Diffractometer Vector 2-axes$ $Diffractometer Reflectometer Reverans$

35 Studies of nanostructures by means of cold neutrons SAPNS Diffractometer Vector 2-axes Diffractometer Reflectometer Reverans 3-axes Spectrometer SESANS hall of cold neutrons

$Diffractometer with very cold neutrons Spin-echo spectrometer with very cold$

36 Studies of nanostructures by means of very cold neutrons 30 Å Å Diffractometer with very cold neutrons Spin-echo spectrometer with very cold neutrons

37 Biological micromolecules and structures: DNA, Proteins, Ferments, Cell membranes. 37

38 Current state of UCN source project at PNPI? 1. Cryogenic and vacuum equipment 2. Design 3. Budget 38

39 Movie How it will be 39

UCN supersource at PNPI and fundamental physics program А.P. Serebrov

UCN supersource at PNPI and fundamental physics program А.P. Serebrov 8 th UCN Workshop Ultra Cold & Cold Neutrons Physics & Sources 11-21 June 2011 1 Content 1. UCN sources at PNPI 2. Ultracold neutron