Dark Matter Search Using High Resolution Emulsion

M. Natsume @Nagoya University

Detection of WIMP arrival direction (not annual modulation)

Sun

220 km/sec

Earth

WIMP wind is due to Sun’s motion through our Galaxy

Observe tracks of nuclear recoils from WIMP

WIMP wind

Detector : Nano Imaging Tracker

high resolution emulsion with 40nm sized AgBr crystal

Compare tracks parallel to the wind with tracks perpendicular to the wind.

keep detector oriented to WIMP wind by rotating mount like equatorial telescope

WIMP

Maxwellian distribution

200 nm

NIT can detect nuclear recoil from WIMP

600 nm

Kr 1200km/sec (600keV)

expose NIT to 84Kr ion beam simulating 81Br recoil

Kr

NIT emulsion layer

15°

SEM

Kr 680km/sec (200keV)

TAC base

enlarge recoil tracks for optical recognition

after development

200 nm

～ 1000 nm

uniform enlargement possible？

WIMP

enlarge !

200 nm

optical image

Enlarge tracks of 5.3MeV alphas from Ra D-E source

before after

2.4 times enlargement

OPERA emulsion

160μm 160μm

１ μm

optical microscope image after enlargement

electron microscope image