Nuclei in matter1

nEDM with Spallation UCN Source of He-II

Y. Masuda (KEK), April 15, 2016, Mainz

+

-dnNeutron

10-1

3 cm

SpinCP violation

shifts charge distribution

μn

EDM cell

nEDM

10-26

10-28

10-24

10-22

10-20

e cm10-30

Theoreticalpredictions

1950 2000

Cold nbeam

UCN

History

1950

2

10-20

10-22

10-24

10-26 e cm

Year

upper limitof nEDM

ρ = 1 UCN/cm3

Pendlebury800 UCN/cm3

A He-II UCN source

E 10 kV/cm

Bo 1

μT

spin s

S matrix: phase operator U(t) = exp{i(μ·B0 + dn∙E)∙t/h}

rotation operator μ, dn ∝ s

EDM cell

1st π/2ωotc precession phase

Our EDM measurement

3

(ω-ωo)tc

ωtc RF phase2nd π/2

Statistical error: 1. N, He-II spallation UCN source2. Pn, Magnetic extraction of UCN from He-II

10-27~10-28 e cm

Systematic error: 3. B0 monitor, 129Xe co-magnetometer 10-27 e cm

The difference (ω-ωo)tc is measured by polarimetry: δdsta = h/{2PnEtc√N}

20K D2O

Ramsey resonance EDM cell

Our nEDM apparatus

VF(guide)= 210 neV

He-IIVacuum

SCM

Al foils

UCN valve is closed during production

2. Magnetic extraction of UCN μB0(3.5T) = 210 neV > VF(Al)=54 neV

10K D2O

300KD2O

12L He-II

Target

Polarized UCN PUCN~100%

Spin analyzerδdsta = h/{2PnEtc√N}

1. UCN production in He-II N∝production rate∝Ep×Ip

EBo

proton beamN∝production time∝τs

Rotary valve

3. 129Xe co-magnetometer

P = 200 UCN/cm3/s, τs = 100 s in 12 L He-II at Ec = 210 new

ρpol = 800 UCN/cm3 in EDM cell of Ec = 90 neV

5

ρ

t τs

ρ = Pτs

P

P (production rate)= ∫∫dEindEUCN

Nσ(Ein→EUCN)dΦn(Ein)/dEin

∝Ep×Ip

Energy deposit upon spallation reaction

target

10K D2OHe-II

Target He-II 10K D2O

400MeV×1μA 0.1 W 4.4 W 400MeV×10μA 1 W 44 W 500MeV×40μA 5 W 220 W (our goal) He-II bottle wall

is dominant

Proton beam power

p beam →

Longer UCN production

6

250 s

123 s

64 s

36 s

600 s

0.8

K

0.9

K

1 K

1.1

K

1.2

K

1370 s

0.7

K

He-II phononup-scatteringGolub, 1983

= 174 s

τβ = 886 s (β decay)

τph = 600 s at 0.8 K

τw = 246 s (wall loss) Z. Phys. B59(1985)261

τ3He = 28 ms at 3He/4He = 1.4x10-6

= 3900 s at 3He/4He = 10-11

τs (UCN lifetime)

= 1/{1/τβ + 1/τ3He + 1/τw + 1/τph}

We are aiming at τs = 100 s

= 174 s

20K D2O

1Kpot

3 He

pu

mp

ing

PulseTubecryostat

4 He pumping

8Lpot

Liq.He

Isopure4He

3He

EDMcell

3Hecryostat

10K D2O

UCNvalve

SCMpolarizer

UCN detector

Doorvalve

3He-4HeHeat

exchanger

300K D2O

7

Target

He-II cooling at 0.8 K

Heating

γ heating are conducted through He-II

Heat load is removed upon3He evaporation.

Proton beam Heatpower He-II400MeV×1μA 0.1 W400MeV×10μA 1 W500MeV×40μA 5 W our goal

3He flow

0.032 mol/s0.16 mol/s

3He pumping

1Kpot

PulseTube

4 He pumping

8Lpot

Liq.Heneedlevalves

3He

Isopure

4He3 H

epu

mpi

ng

3He-4Heheat

exchanger

He-II

20K D2O10K D2O

Target

104 m3/h

pump3He reserver

Pre-coolingfrom 300Kto 30K

Heating

3He of 0.16 mol/s at Ep×Ip = 20 kW is returned to cryostat

φ12→φ25

φ12

γ heating are conducted through He-II

Cooling power3He evaporation rate

3Hefilling

0.16mol/s

0.24 mol/s at 0.7 K

20K D2O

1Kpot

3 He

pu

mp

ing

4 He pumping

8Lpot

Liq.He

Isopure4He

3He

PulseTube

UCN sourceGM cryostat

10K D2OHe-II

UCNvalve

SCMpolarizer

UCN detector

Doorvalve

300K D2O

9

Present status of our UCN source

SteelConcrete GraphiteTarget

Exhaustvalve for

bottle cleaning

3Hecryostat

3He-4HeHeat

exchanger

EDMcell

Superconductingmagnet

3He cryostat

UCN source

Photo of our UCN source

10

He-II

Heatexchanger

3He circulator

SuperconductingUCN polarizer

Isopure 4Hecirculator

GM cryostats andHe recovery line

Peripherals3He-4He heatexchanger

He-II

Heat load from outside

SCM for UCNextraction

B0

Heatexchanger

was 1 W

40K radiation shield

Replaced Be-Cu with stainless steel for better thermal insulation

to the horizontal UCN guide and the UCN extraction part,

0.3 W 0.2 W

Added4K radiation shield

Superconductingmagnet

3He cryostat

UCN source

Increasing UCN production rate from 4 to 200 UCN/cm3/s at Ec = 210 neV

3He pumping of 2000 m3/h

Heat load on He-II 1 W 0.3 W 0.2 W3He evaporation 32×10-3 mol/s 9.6×10-3 mol/s 6.4×10-3 mol/s He-II temperature 0.7 K 0.6 K 0.58 K

10000 m3/h for 5W (10 W) Ep×Ip = 20 kW

13

We have achievedcooling power of 1 W at 0.7 K (2 W at 0.8 K)

Ep×Ip = 4 kW (8 kW)

20K D2O

1Kpot

3 He

pu

mp

ing

4 He pumping

8Lpot

Liq.He

Isopure4He

3He

PulseTube

UCN sourceGM cryostat

10K D2OSCM

polarizer

UCNdoublevalve

UCN detector

Spinanalyzer

Spinflipper 300K D2O

14

He-II

TargetGraphiteSteelConcrete

3He cryostat

UCNvalve

UCN production and polarized UCN extraction

UCN guide

UCN spin flipperanalyzer

UCN detector

UCN production

UCN polarization

3He cryostat

SuperconductingUCN polarizer

15

Effect of holding field

Preliminary

to be published

Preliminary

VF(guide)= 210 neV

He-IIVacuum

SCMB0

Al foilsUCN was counted as a function of valve opening time Including Al foils

B0 = 0 → 3.5 T τ = 20 → 40 s

τ = 9 s

UCN transmission is enhanced ! μB0(3.5T) = 210 neV, VF(Al) = 54 neV. He-II UCN valve is effective !

16

UCN storage lifetime in He-II

PreliminaryPreliminary

He-II

Increasing UCN storage lifetime to 100 s

Wall loss

VE < V

We need material of low absorption and high Fermi potential

loss/collision:μ = 2f ∫{Ecos2θ/(V-Ecos2θ)}1/2

cosθ d(cosθ) f = W/V optical potential U = V - iW = 2πh2/m N (ar - iai) Im f(0) = k/4π σtot

σtot = σinela + σa

3He absorption: τ3He = 3900 s at 3He/4He = 10-11

He-II

electropolished SUS316L Ra < 2 nm electropolishedaluminum

58Ni coated pipegood heat conduction

Suitable wall material

In future, Be pipe or DLC coating? UCN valve

We need material of lower f = W/V !

for τ > 100 s

The material should sustain at the low temperature !

NiP → 58Ni → Be pipe or DLC coating?

20K D2O

1Kpot

3 He

pu

mp

ing

4 He pumping

8Lpot

Liq.He

Isopure4He

3He

PulseTube

10K D2OSCM

UCN detector

Spinanalyzer

Spinflipper

Rotaryvalve

Doorvalve

19

He-II

Target

GraphiteSteelConcrete

nEDM, KEK-Osaka-RCNP

H.V.

EDMcell

3He cryostat

1. He-II UCN productionin spallation source

2. Magneticextraction of UCN

from He-II

3. nEDM with 129Xe co-magnetometer

nEDM apparatus connected to the UCN source

SuperconductingUCN polarizer

3He cryostatCompensationcoils

SpallationUCN source

Ramsey resonance apparatus

Permalloyshield

Ramsey resonance apparatus

π/2 RF coilEDM cell

Spherical coil for B0

UCN valveDoor valve

21

Iron magnetized

foil

Spin flipper

Rotary valve

UCN detector

Old source

Ramsey resonance

(ω-ωo)tc =

-4π-2π0 2π 4π

-5π-3π

-π π3π

5π

��

����

����

����

����

��� �� ��� �� ����

� �������������������� ���

������������������������µ��

������������ �� 200 mG

measured by old source

22

nEDM is measured from shift upon E reversal B0 stability

23

B0 monitor: 129Xe spin precession

M. Mihara

Bo

EDM cell

129Xe

λ = 252 nmδν < 1 GHzP > 0.5 WBeam size< 50 μm

photon detector

x8

μ

IR photons

t 10-27 e cm

5 days of measurement δB0 = 0.3 fT

P129Xe = 3 mmTorr

895.5nm823.4

nm

-1/2

2GHz

+3/2

+1/2

+5/2+3/2

F=3/2F=5/2

5p5(2P3/2)6p(2[3/2]2)

5p5(2P3/2)6s(2[3/2]1) 5p5(2P3/2)6s(2[3/2]2)

5p6(1S0)6s F=1/2

252.5 nm ×2δMF = +2

σ+

T. Chupp

129Xe level scheme

Rb-Xe spin exchange optical pumping

B0 solenoid coil

B0 = 4.3 mT

B1 coil

pickupcoilσ+

B1 (ν = 51.5 kHz)0.3

0.2

0.1

0.0

-0.1Lo

ck-in

out

(V)

543210t (s)

B0

Xe 10 TorrN2 750 Torr

enriched Xe(129Xe 86%)156 °C

natural Xe(129Xe 26.4%)141 °C

We have achieved129Xe polarization of 70%

Happer

1Kpot

PulseTube

4 He pumping

8Lpot

Liq.Heneedlevalves

3He

Isopure

4He3 H

epu

mpi

ng

3He-4Heheat

exchanger

He-II

20K D2O10K D2O

Target

104 m3/h

pump3He reserver

We are remodeling cryostat for safety

Present helium venting tube complies with ASME

at normal vacuum loss.

He ventingupon

vacuum failure

For sudden huge vacuum loss, we are now working on reconstructing the cryostat.

P = 4 UCN/cm3·s at Ec = 210 neV, Ep×Ip = 0.4 kW (2012)→ 200 UCN/cm3·s in 12 L He-II 20 kWτs = 81 s (2012) → 100 s

Statistical error: 10-27~10-28 e cm 1. He-II UCN production in spallation n source

2. Magnetic extraction of UCN from He-II

Systematic error: 10-27 e cm 3. 129Xe co-magnetometer

PUCN = 90% at the EDM cellvisibility α = 83 %

Our nEDM

ρpol = 800 UCN/cm3 in the EDM cell of Ec = 90 neV

Thanks