Zhimin Wang
Liu Ruoqing, Tang ChenYang,
Charling Tao, Changgen Yang , Changjiang Dai,
Tsinghua & IHEP
2014-10-12, Shanghai
A Simple New Gas Detector
Developed by Ioanis Giomataris, Saclay, France
• Natural focusing:
– large volumes can be instrumented
with a small readout surface and few
(or even one) readout lines
• 4p coverage: better signal
• Still some spatial information
achievable:
– Signal time dispersion
• Other practical advantages:
– Symmetry: lower noise and
threshold with large volume
– Low capacity
– No field cage
• Simplicity: few materials. They
can be optimized for low
radioactivity.
• Low cost
2
A prototype





D=1.3 m
V=1 m3
Spherical vessel
made of Cu (6 mm
thick)
P up to 5 bar
possible (up to 1.5
tested up to now)
Vacuum tight: ~10-6
mbar (outgassing:
~10-9 mbar/s)
Typical spectra
5
Run with Ar/CH4 + 3g 3He @ 200 mb
SPC 130cm Ø @ LSM
NB: no start
=> risetime records
place and/or history
of energy deposition
Rise time (s)
If localised energy
deposition, rise time
depends of radius
(diffusion)
 210Po
5.3 MeV
n capt on 3He
764 keV
alpha
If track, rise time
depends on
orientation of track
(different drift times)
222Rn 218Po 214Po
derivative
de/dx
Amplitude
6
Run with Ar/CH4 + 3g 3He @ 200 mb
SPC 130cm Ø @ LSM
Taux 400 capt/j
n capt on 3He
=> p + T
Rise time (s)
 210Po
5.3 MeV
 210Po
5.3 MeV
from 210Pb
@ Cu surface
R = 15 cm
n capt on 3He
764 keV
1
2
3
222Rn 218Po 214Po
Unwanted Radon
daughter deposit on
surface
Amplitude
2 : fast neutron expected here
7
Basic performance

Mixtures tested:
– Ar+10% CO2
– Ar+2% Isobutane
Pressures from 0.25 up to
1.5 bar tested up to now
 High gains (>104) achieved
with simple spherical
electrode
 No need to go to very high
V (better for minimizing

absorption)
Applications
– Dark Matter
– Coherent neutrino scattering
– Double beta decay
– Axion
– SN neutrino monitoring
----------------------------------------------------------------------------------– Neutron spectroscopy
– Neutron counter for industrial application
– Low level neutron counting
– Radon low level counting
– Atmospheric neutron and Muon monitoring
– Gamma ray spectroscopy in harsh environment
– …
Some physics applications
arXiv:1401.7902 Gerbier et al.
DM WIMP
Reactor neutrino
10
doi:10.1088/1742-6596/203/1/012030
LSM neutron flux
From Savvidis ilias
An international working group “NEWS”
from G. Gerbier
Activities at IHEP &Tsinghua
Detector performance studies
Plan to measure neutrons in Jinping with 1g He3
14
STPC goals
• NEWS network: 4m detector. Where?
Jinping?
SNO? Gerbier in Canada with 10 M$ grant
• Training for low radioactivity gaseous detector for
large volume TPC
 Solar neutrino (HELLAZ like)
 Directional Dark Matter (also an old idea!)
15
Hellaz simulation (1997?)
1995-1998 The HELLAZ solar pp neutrino project Tom Ypsilantis,
Jacques Séguinot et al… , with a Micromegas
16
Dark matter detection with hydrogen proportional
counters
G. Gerbier, J. Rich, M. Spiro, C. Tao
Nuclear Physics B - Proceedings Supplements
Volume 13, February 1990, Pages 207-208
Comments : for some DM types
not Mass but Number of nuclei is important
Gaseous detectors are beautiful !
•
•
1975-1979 Cylindrical Drift chamber in PhD thesis back for Fermilab
DIS muon CHIO in Smithsonian (Washington DC)
1979-1982: UA1 Central Detector
1st W event in UA1 CD
Personal interest for > 20 years
Technology OK and keeps improving
For DM: needs detection from >2 nuclei
AND directionality!!!
Is our science case compelling enough?
CDM vs WDM debate
Directional DM Detectors
• CYGNUS 2013: 4th Workshop on Directional
Detection of Dark Matter Tatsuhiro Naka and Kentaro
Miuchi - 2013 J. Phys.: Conf. Ser. 469 011001
Workshop Series Boulby 2007 , MIT 2009, Aussois 2011
• Many projects: DMTPC, NEWAGE, DRIFT, MIMAC
• emulsions
MIMAC
MIMAC bi-chamber prototype 1311.0616
• The MIMAC bi-chamber prototype is composed of two chambers sharing
the same cathode being the module of the matrix
• active volume (V 5:8 l)
• 70%CF4 + 28%CHF3 + 2%C4H10 at a pressure of 50mbar. The primary
electron- ion pairs produced by a nuclear recoil in one chamber of the
matrix are detected by driving the electrons to the grid of a bulk
micromegas and producing the avalanche in a very thin gap (256 mu).
• Track reconstruction in MIMAC. The anode is read every 20 ns. The 3D
track is reconstructed, from the consecutive number of images
Bi-chamber prototype at the
Laboratoire Souterrain de Modane
The bi-chamber prototype at the Laboratoire Souterrain de Modane in June
2012. The bi-chamber module is identified in red and the bluer volume in blue.
The position of peaks of Cd (3.2 keV), Cr (5.4 keV), Fe (6.4 keV), Cu (8.1 keV) and Pb (10.5 and
12.6 keV) tted by a linear calibration in ADC channels as a function of time, highlighting the
gain stability during the data taking period.
4. Preliminary analysis of the first months of data taking
The first available data set of the bi-chamber prototype was started on July 5th 2012
Background in LSM
23
Electron vs nuclei recoil
The length [cm] vs. Energy [ADC channel] of electrons and proton recoils produced by
neutrons of 144 keV in pure isobutane (C4H10) at 50 mbar. The maximum of the proton
energy corresponds to 144 keV. (Right): The NIS (normalized integrated straggling) for recoil
events (in black) and for electrons (in blue).
24
25
1.5 keV He4
recoils
26
3D-Track reconstruction 34 keV
Some tracks in MIMAC
8 keV hydrogen nucleus in 350 mbar 4He+5%C4H10, a fluorine nucleus leaving 50 keV in
ionization in 55 mbar (70% CF4 + 30% CHF3) and a 5.5 MeV alpha particle in 350 mbar
4He+5%C4H10
28
29
MIMAC 1m3 in preparation
WIMP distribution
32