Emmanuel MOULIN

1
Project of a new generation detector for direct
detection of non-baryonic dark matter MACHe3,
MAtrix of Cells of superfluid Helium 3

• LPSC-CRTBT-LTL Collaboration
• LPSC (Grenoble) E. Moulin, F. Naraghi, D.
  Santos
• CRTBT (Grenoble) Yu. M. Bunkov, H. Godfrin,
  C.Winkelman
• LTL (Helsinki) M. Krusius

• Emmanuel MOULIN
• LPSC (ex-ISN) - Grenoble

E.MOULIN 4th Marseille Internat. Cosmology
Conference 24/06/03 1
2
Main topics

• MACHe3 project
• Results from first experiment
• Neutralino detection phenomenology
• Next steps

E.MOULIN 4th Marseille Internat. Cosmology
Conference 24/06/03 2
3
3He for non-baryonic DM search
3He in B phase at T 100 ?K

• spin 1/2 nucleus ? axial interaction with
  neutralino
• high purity ? no radioactive contamination
• neutron capture signature
• very low sensitivity to ? rays
• no intrinsic X rays
• detection threshold 1 keV
• high signal/noise ratio

E.MOULIN 4th Marseille Internat. Cosmology
Conference 24/06/03 3
4
MACHe3 project (1)

• 10 kg of superfluid 3He

1000 bolometric cell matrix
a Lancaster type bolometric cell

• VWR (Vibrating Wire
• Resonance) damping
• thermal diffusion through
• the hole

E.MOULIN 4th Marseille Internat. Cosmology
Conference 24/06/03 4
5
MACHe3 project (2)
Rejection

• neutralino in 1-6 keV range
• ? high signal/noise ratio
• correlation between cells

Background events

• gammas from natural radio-
• activity (40K, Rn,)
• ? lead shielding 15 cm
• neutrons
• ? paraffine shielding 30 cm
• ? capture process signature
• muons
• ? many cells fired

E.MOULIN 4th Marseille Internat. Cosmology
Conference 24/06/03 5
6
Total rejection simulation (Geant4)
for 1000 cells of 100 ?m Cu thick

• neutron capture process
• ? good neutron rejection

E.MOULIN 4th Marseille Internat. Cosmology
Conference 24/06/03 6
7
Experimental results on prototype cell
cryostat
lead shielding
E.MOULIN 4th Marseille Internat. Cosmology
Conference 24/06/03 7
8
Raw data at 100 ?K
50 keV muon deposit
Raw spectrum
Sensitivity
structures at 1.5 keV
peaks at 11.2 keV
1 keV
E.MOULIN 4th Marseille Internat. Cosmology
Conference 24/06/03 8
9
Data analysis
data and noise adaptative filter
peaks in the 1-10 keV range with white noise
Gain 10
1 keV peak
? 1 keV peak is detected
E.MOULIN 4th Marseille Internat. Cosmology
Conference 24/06/03 9
10
Neutron detection
n 3He p 3H 764 keV

• (Am/Be source)
• peak at 650 keV
• energy resolution
• of 3

• shift ( 14) UV photon emission, vortex
  creation ?

E.MOULIN 4th Marseille Internat. Cosmology
Conference 24/06/03 10
11
Muon detection (in prototype cell)
Experimental data ? peak at 52 keV

• Geant4 simulation
• peak at 67 keV

• shift (22) ? UV photon emission

E.MOULIN 4th Marseille Internat. Cosmology
Conference 24/06/03 11
12
? MACHe3 3He-? cross-section
large scan of SUSY para- meter space
0.01 per day ? ultimate background
F. Mayet et al. Phys. Lett. B 538 (2002) 257
E.MOULIN 4th Marseille Internat. Cosmology
Conference 24/06/03 12
13
Complementarity with scalar direct detection

• axial and scalar signals
• not correlated
• MACHe3
• rate gt 0.01 day-1

F. Mayet et al. Phys. Lett. B 538 (2002) 257
E.MOULIN 4th Marseille Internat. Cosmology
Conference 24/06/03 13
14
Next steps (1)

• ? test correlation
• between cells with
• a new acquisition system
• ? lines at 7, 14 , 115 et 129 keV

• Multicellular prototype

3 small cells
vibrating wires

• Low energy calibration with an
• electron conversion source (57Co)

E.MOULIN 4th Marseille Internat. Cosmology
Conference 24/06/03 14
15
Next steps (2)

• Scintillation detection

? detection of UV photons (with SQUID) in
progress opportunity for
scintillation/bolometer technique? ? in
different SUSY models (mSUGRA, AMSB, GMSB)
performance and complementarity with existing
detectors

• Neutralino detection phenomenology

E.MOULIN 4th Marseille Internat. Cosmology
Conference 24/06/03 15
16

8 keV copper X rays simulation(Geant4)

• X rays deposited energy in a 3He cell is
• either higher than 6 keV
• or lower than 1 keV

99.997 8 keV X rays depose less than 1 keV or
more than 6 keV
Event range

• Cu radioactivity 3 mBq/kg
• background for 10 kg
• matrix 5.10-2 jour-1
• (for 100 ?m thick cell)

E.MOULIN 4th Marseille Internat. Cosmology
Conference 24/06/03 16
17
Matrix parameters
Ni incident particle number N particle number
giving a signal in matrix N1 unicellular event
number N6 unicellular event number giving less
than 6 keV M1,M6 defined as N1,N6 but for events
out of veto

• Cgeo N1/N
• Rener N1/ N6
• Cveto N1/M1
• Rint N/M6
• Rtot Ni/M6

E.MOULIN 4th Marseille Internat. Cosmology
Conference 24/06/03 17
18
Gamma rejection

for 1000 cells of 5 cm large and 100 ?m Cu thick

_______________________________ E.MOULIN 4th
Marseille International Cosmology Conference
24/06 15
E.MOULIN 4th Marseille Internat. Cosmology
Conference 24/06/03 18
19
Neutron rejection
for 1000 cells of 5 cm large and 100 ?m Cu thick

E.MOULIN 4th Marseille Internat. Cosmology
Conference 24/06/03 19
20
Background rejection

• In a 10 kg matrix of 1000 cells in the LSM
• (underground laboratory)

• Monte carlo simulation
• neutron background (30 cm paraffine) 0.1 day-1
• muon background 0.01 day-1

F.Mayet et al. Nucl. Inst. M.eth. A 455 (2000)
554
E.MOULIN 4th Marseille Internat. Cosmology
Conference 24/06/03 20
21
?? detection phenomenology

• SUSY model phenomenological MSSM
• 6 free parameters
• M2, ? jaugino and higgsino mass parameters
• m0 common scalar mass
• MA pseudo scalar Higgs mass
• tan ? Higgs vev ratio
• At,b trilinear couplings
• DarkSUSY code, large SUSY scan 2.106 models
• Parameters Min Max
• ? (GeV) 50 103
• M2 (GeV) 50 103
• m0 (GeV) 100 104
• MA (GeV) 100 103
• tan ? 3,10 and 60
• At,b 0

E.MOULIN 4th Marseille Internat. Cosmology
Conference 24/06/03 21
22
? Sensivity area MACHe3/scalaire
F. Mayet et al. Phys. Lett. B 538 (2002) 257

• for ? lt 0 scalar interaction is suppressed
• this is not a general trend!

E.MOULIN 4th Marseille Internat. Cosmology
Conference 24/06/03 22
23
? Comparison with indirect detection ?

• ?(Earth) ? ?scal non correlated
• ?(Sun) ? ?scal and ?spin complementarity

F. Mayet et al. Phys. Lett. B 538 (2002) 257
E.MOULIN 4th Marseille Internat. Cosmology
Conference 24/06/03 23
24
? Sensitivity area MACHe3/?
F. Mayet et al. Phys. Lett. B 538 (2002) 257

• ? telescope sensitive to higher masses
• large SUSY region is reached

E.MOULIN 4th Marseille Internat. Cosmology
Conference 24/06/03 24