UCN detection (UWpg, UofM, TRIUMF)• principle • high rate capability• Li glass scintillators + lightguide + PMTs• molecular sticking technique of 6Li

enriched and depleted scintillators

UCN in the Meson Hall at TRIUMF

Canada's National Laboratory for Particle and Nuclear PhysicsLaboratoire national canadien pour la recherche en physique

nucléaire et en physique des particules

Progress towards a next generation UCN source at TRIUMF

R. Picker1, T. Adachi2, K. Asahi3, C. Bidinosti4,5, J. Birchall5, C. Davis1, F. Doresty5, W. Falk5, M. Gericke5, K. Hatanaka6,

B. Jamieson4,5, S. C. Jeong2, S. Kawasaki2, A. Konaka1, E. Korkmaz7, M. Lang5, L. Lee1, R. Mammei4, J. Mammei5,

J. Martin4,5, Y. Masuda2, R. Matsumiya6, K. Matsuta8, M. Mihara8, A.Miller1, E.Miller9, T. Momose9, D. Ramsay1, S. Page5,

E. Pierre1,6, Y.Shin1,6, H. Takahashi2, K.H. Tanaka2, I. Tanihata6, W. van Oers1,5, Y. Watanabe2

(1) TRIUMF, Vancouver(2) High Energy Accelerator Research Organization (KEK), Tsukuba

(3) Tokyo Institute of Technology, Tokyo(4) University of Winnipeg, Winnipeg(5) University of Manitoba, Winnipeg(6) RCNP, Osaka University, Osaka

(7) University of Northern British Columbia, Prince George(8) Department of Physics, Osaka University, Osaka

(9) University of British Columbia, Vancouver

Developments for a next generation nEDM measurementMagnetic shielding (UWpg)• active shielding• 4-layer ferromagnetic shield prototype• 1.59 mm thick Aperam® mu metal• theoretical DC shielding factor >106

• evaluate magnetometry (fluxgates, GMI, NMOR sensors)

• delivered to UWpg 8/2013

Kicker magnet:• 480 MeV protons • 12 mrad deflection • rise and fall time < 50 s• aperture 100x100 mm2

• 330 Hz max rep rate• maximum current 240 A• voltage during ramping 1300 V• ordered from Danfysik 8/2013

Bending dipole• provided by KEK• field 0.39 T• deflection of beam 7°• already constructed and mapped,

ready for shipment to TRIUMF

Steering quads• conventional magnets• on hand at TRIUMF

Cold moderator cryostat• optimization ongoing (see below)

3

3

Co-magnetometer (UBC, SFU)• dual approach: 129Xe + 199Hg• correct for geometric phase

effect (GPE) due to opposite magnetic moment

High voltage, EDM cell (TRIUMF)• dielectric strength of Xe at 10-3 mbar

unknown• HV test setup at TRIUMF• 50x100 mm cylindrical test cell• field strength goal > 10 kV/cm• test of different cell materials• commissioned 8/2013

129Xe 199Hg

form at RT inert gas delicate liquid

magn mom ‐0.7768  +0.5059

excitation, wavelength

2 photon252.2 nm

1 photon253.7 nm

n abs xsect 21 barn 2150 barn

atomic EDM < 10-27ecm <10-29ecm

n+6Li→3H (2.74 MeV) +4He (2.05 MeV)

n

Xe inlet

HV feed

HV cell

Lambertson septum:• beam separation in center 70 mm• adaption of available Parity Dipole• pole & lower coil moved up to

relocate gap near bottom• tilt around beam axis 4.4°• deflection of beam 9°• TRIUMF machine shop is working

on modifications

2.5 m

0.75 m

Shielding pyramidview from opposite direction

Optimization of cold moderator for TRIUMF phase

• lead multiplies spallation neutrons and shields cryostat from target gamma rays, while storing no Wigner energy

• D₂O at 300 K moderates and thermalizes the neutrons

• liquid D₂ at 16°K (71% ortho.) increases the neutron yield at 1 meV further

• these slow neutrons emit phonons in He-II → UCNs

• beryllium absorbs few neutrons, not heating cryostats (but: expensive)

• using liquid D2 instead of solid D2O increases UCN yield and allows further optimization

• MCNPX and MicroShield® have been used• current most promising setup

– decreases heating of He-II from 8.4 to 2.9 W– increases UCN yield by a factor of up to 20

spallation target

• existing design for a few A at RCNP problematic for 40 A at TRIUMF

– sdfas Wigner energy from graphite high dose rate during

disassembly

0.8 K He-IIUCN guide

10 K sD20

300 K D20

aluminumgraphite

spallation target

0.8 K He-IIUCN guide

16 K D2

300 K D20

berylliumlead

graphite

1 m

300 K D20

graphite

Spallation target• beam power: 20 kW (during 1 min beam

on target) and 5 kW (average)• inspired by KEK design• tantalum-clad tungsten blocks “HIP”-

ing process• water cooled

Superconducting polarizer • provided by RCNP• maximum field 3.8 T• HTC conductor (BSCCO)• cooled via He exchange gas to 20 K• polarizing potential with Al foil:

283 neV• tested at RCNP 7/2013: no quench

6Li depletedon6Li enrichedscintillator

light guides

PMTs

He-II cryostat• provided by KEK/RCNP• pumping on 3He • isopure 4He convertor at 0.8 K• 32 l of 4He• first full cool down 7/2013:

0.73 K