Download 1time/100kg day），producing atomic recoil， Direct detection of dark

Dark matter forms a giant sea,
enclosing the milky way. The
earth and solar system like a
small fish, swimming in it.
 Dark Matter particle has a small
probability hitting the atomic
nuclei (<1time/100kg day），
producing atomic recoil，

Direct detection of dark matter is to detect the
Signals produced by this type of atomic recoil.
Phonon
Electron
Photon

Semi-Conductor（Ge，Si）
 Electric current and heat
 Low -T（0.02K）、high-cost， hard to scale

Crystal（NaI， CsI）
 light
 Hard to rule out background

Noble gas-liquid (Xe，Ar）
 Light and electrons
 Good to distinguish signals，ton scale

We are on the verge of discovery!
Dark Matter Rush!

Can detect both light and electron：
 light：through PMT
 electrons：strong electric field+ gas phase


Large target：large target has self-shielding effects
Large atomic mass
 Cross section is proportional to the square of A


Can be purified easily
Is complementary to the semi-conductor tech


10kg Xe
Gran Sasso


Upgrade of XENON10
Lower background than
XENON10 by 100 times，
background
0.005 event／kg day kev
Can discriminate gamma
and nucear recoil by 99.5%
 Continuous running since
jan 2011



Started in 2009
Major Institutions
 Shanghai Jiaotong University
 Shanghai Inst. of applied physics
 Shangdong University
 Peking University
 University of Michigan
 University of Maryland
JinPing Hydropower plant
has four water-passage
tunnels of 13m diameters,
two traffic tunnels of 6m
diamters.
Length of the tunnel, 17km
 Maximum depth 2400m
(6000-7000 wm).

Shield
Cooling Bus
Xe
Storage