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

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1 UCN supersource at PNPI and fundamental physics program А.P. Serebrov 8 th UCN Workshop Ultra Cold & Cold Neutrons Physics & Sources June

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

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

5 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 5

6 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 6

7 10 7 n/(сm 2 s А) С UCN generation (0.9±0.

7 H.Yoshiki experiment at ILL Phys. Lett. A 308 (2003) neutron count storage time, s temperature, K wavelength, A UCN density in the source ρ=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 7

8 Project of ultracold and cold neutron source with superfluid helium at WWR-M reactor 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. UCN λ=500 Å, T=10-3 K CN λ=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 sa) 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 кw Ф=10 14 n/(cm 2 s) Q=15 MW 11

12 UCN density maximal density inside closed source density in experimental trap with volume 35 l density in experimental trap with volume 350 l 12

13 Cryogenic scheme of UCN source with superfluid He More details in talk of A. Zakharov (this workshop) 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 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. 13

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

15 General design 15

16 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. 16

17 New facilities of WWR-M reactor 17

18 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 18

19 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 and neutron - mirror neutron oscillations 4. Search for long-range forces 5. Search for dark matter with long-range forces 19

20 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 20

21 Problem of CP-violation and Neutron EDM 21

22 PNPI-ILL nedm collaboration More details in talk of E. Kolomensky (this workshop) 22

23 Neutron EDM and problem of CP-violation 23

$Crystal-diffraction nedm More details in talk of V.$

24 Crystal-diffraction nedm More details in talk of V. Fedorov (this workshop) Monitor Beamstop (110) plane Meissner cavity T=T 0 ±Δ PG (002) (R~50%) outgoing nutator T=T 0 incoming nutator SM polarizer Double crystal PG monochromator Beamstop (110) plane 3 He cell H L 0 Y Z Spin flipper PF1b npsd E n <E 0 +P v D n +E -E X. E n >E 0 -P D Quartz crystals 24

25 nedm projects and collaborations USA (ORNL) Switzerland (PSI) France (ILL) Japan-Canada (KEK-RCNP-TRIUMF) 25

26 Neutron decay, Standard Model and Cosmology 26 26

27 Neutron β-decay and Standard Model u n d d W - CKM mixing matrix: GV = GF Vud u d p u eē ν d Vud Vus Vub d s = V V V s cd cs cb b Vtd Vts V tb b k ft( 1+Δ )( 1+δ ) = Vud GF 1+ 3λ ~1.5 % ~2.4 % G λ( λ+ 1) A 2 V G A A λ= 0 = 2 GV 1+ 3λ ± 1.9 s 2 ud = τ 2 n + λ ( 1 3 ) G V ( ) R R W.Marciano A.Sirlin PRL 96, (2006) Required experimental accuracy for τ n and A has to be about

28 Neutron decay and cosmology G. J. Mathews, T. Kajino, T. Shima, Phys. Rev. D 71, (R) (2005) G f 1 3 g m 3 2π n A e F ( τ ) = ( + ) τ n, world average τ n, Gravitrap result ( ) ( ) Δτ = 1% Δ Y=0.75% ± 0.61% n Δτ = 1% Δ η=17% ± 3.3% n New τ n =(878.5±0.8) s confirms n b /n γ from CMB. 28

29 Big Gravitational Trap. Project accuracy of neutron lifetime measurement 0.2 s More details in talk of A. Fomin (this workshop) 29

30 UCN trap of permanent magnets More details in talk of V. Ezhov (this workshop) 30

Project on neutron β-decay A-asymmetry measurement y - [mm] 60 50 40

=39 o, E e =200 kev proton detector magnetic strength, H [A/m] [ T ]

4000 H m Z - [mm] β-decay area H 0 p-detector 0,1 0,0 0 0 0 2 1000 4

H 0 = 0.35 T ΔH 0 /H 0 = 2 10-3 210 mm, L=2690 mm H m = 0.

31 Project on neutron β-decay A-asymmetry measurement y - [mm] electron detector neutron beam θ c =39 o, E e =200 kev proton detector magnetic strength, H [A/m] [ T ] 0,9 8 0,8 0,7 6 0,6 0,5 4 0,4 0,3 2 0,2 e-detector H m Z - [mm] β-decay area H 0 p-detector 0,1 0, distance, z [mm] sin 2 θ c = H 0 /H m θ c = 39 H 0 = 0.35 T ΔH 0 /H 0 = mm, L=2690 mm H m = 0.87 T ΔH m /H m = mm, L=50 mm dcosθ eσ = cosθ eσ eσ cosθ =

32 Other topics 1. Search for long-range interaction talk of O. Zherebtsov (this workshop) 2. Search for dark matter with long-range forces talk of A. Serebrov (this workshop) 32

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 34

$Studies of nanostructures by means of cold neutrons SAPNS Diffractometer Vector 2-axes$

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 35

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

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 36

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

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

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