Status of Dark Matter and Neutrino Physics

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Status of Dark Matter and Neutrino Physics
ETTORE MAJORANA FOUNDATION AND CENTRE FOR
SCEINTIFIC CULTURE INTERNATIONAL SCHOOL OF
SUBNUCLEAR PHYSICS 47TH COURSE THE MOST UNEPECTED
AT LHC AND THE STATUS OF HIGH ENERGUY
FRONTIER 29 August - 7 September 2009
A. Bettini Università di Padova, Dipartimento di
Fisica G. Galilei INFN - Sezione di
Padova Laboratorio Subterráneo de Canfranc
(Huesca) Spain
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The Models
Cosmology is now exact Tested by consistency by
observations _at_ different epochs
The Standard Model is the most precise and
comprehensive theory ever built Tested with high
accuracy in experiments _at_ accelerators
80 of matter is non baryonic

• The Standard Model of Subnuclear Physics explains
  5 of the universe
• The Standard Model of Cosmology accounts the rest
  with
• A dark matter we dont see
• A dark energy we dont understand

• We have hints on what to search for
• new elementary particles (WIMPs, Inflaton,..)
• new elementary vacuum

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The matter density in the Universe
WMAP (and others) data on CMB At t372 000 y dark
matter shaped the primordial density fluctuations
through its gravitational potential
GLOBAL FIT H070.51.3 km/(s Mpc) Wmh2
0.13580.0037 Wb0.04560.0015 h2 (H0/100)2 ?
0.5
Independent evidence at t few seconds. D2
nucleosynthesis ? h2Wb0.0200.002
The largest fraction of matter is not baryons
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Cold Dark Matter is still in the Universe
Bullet clusters
Independent astrophysical data at different
epochs give a common value of matter density
Wm?0.30
Largest fraction of the mass is non baryonic and
dark
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Dark Matter is not Neutrinos

• Is non-baryonic dark matter made of neutrinos?
• ns were cold _at_ last scattering epoch ? little
  effect on CMB spectrum z1089
• at the epoch of LSS formation (z0.1-0.2) ns
  could freely stream above them, reducing the
  growth rate ? effect _at_ few tens of Mpc (today
  scale)

Two surveys SDSS and 2dFGRS
fnWn/Wm lt 0.015
Largest fraction of the dark matter is
non-relativistic cold
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Dark matter is here and now
Cold dark matter is present at all scales
including galactic halos (rotation curves),
including ours (revolution speed of Magellanic
Clouds, etc.) If dark matter particles do not
have weak interaction, no hope to detect them, if
they do are called WIMPs NB. Not necessarily only
one type
WIMP speed distribution assumed to be
Maxwellian Speed in order of magnitude ltbWgt ?
103, similar to stars, similar to atomic
electrons Expected density rW? 300 TeV m3 For
MW ? 100 GeV number density, n ? 3000/m3 flux
FW ? 109 s1 m2 Typical kinetic energy Ekin50
keV or less
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Tiny signals. Go underground
Discovery in underground laboratories with
natural sources (sun, cosmic rays), and long
base-lines Confirmation and improvement in
precision with reactor and accelerator
experiments, on unprecedented baselines
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Lepton mixing

• Neutrinos change flavour in two different ways
• (vacuum) oscillation
• in the kinetic part of the Hamiltonian
• observed in nm produced by cosmic rays in the
  atmosphere
• does not depend on qij?p/2qij but for 2nd
  oscill. interf.
• does not depend on sign(Dm2) but for 2nd oscill.
  interf.
• flavour conversion in matter (Sun, Supernova,
  Earth)
• dynamical phenomenon, due to the nee interaction
  potential (2GFne)
• observed in solar nes
• depends on qij?p/2qij
• depends on sign(Dm2)

qij
qij
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Mas eigenstates - Flavour eigenstates
9 quantities to be measured 3 msses, 3
phases 3.5 known Global fir by Fogli et al., 2?
uncertainties (95 c.l.)
quark q1212.9 q232.3 q130.2
q12 34 q23 45 q13lt 10 (95)
Fogli et al. hep-ph/0506083v2 Progr. Nucl. Phys.
57 (2006) 742-795
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What do we know?
Define n1, n2, n3 in decreasing order of ne
fraction n1 ?? ? 70 ne, n2 ?? ? 30 ne, n3 ?? ?
0 ne solar squared mass difference ?
dm2m22m12 ( gt0 from solar neutrinos) atmospheri
c squared mass difference ? Dm2m32(m22 m12
)/2 Global fir by Fogli et al., 2? uncertainties
(95 c.l.)
Fogli et al. hep-ph/0805.2517v2

• We do not know
• The absolute scale
• The sign of Dm2

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Hints for ?13?0
Fogli et al. arXivhep-ph 09053549v2 Balantekin
and Yilmaz, J. Phys. G 35, 0705007 (2008)
2008. Tension between Kamland and Solar data
ALL TOGETHER 2? NOTHING SERIOUS YET
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MSW and oscillations in the sun
Mass eigenstate in high density matter in the
core ? ne Neutrinos moving toward the surface
meet resonance condition if E?gt few MeV ?
MSW The highest energy neutrinos (E??10 MeV )
leav the sun almost in mass eigenstate n2 At
low energy oscillation like in vacuum
_at_ sun densities, the resonance is _at_ ?m2 Relevant
angle is ?12, which is large ? adiabatic
Transition not yet directly tested experimentally
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BOREXINO - Detector layout
Stainless Steel Sphere 2212 photomultipliers
1350 m3
Scintillator 270 t PCPPO in a 125 ?m thick
nylon vessel
Water Tank g and n shield m water Ch
detector 208 PMTs in water 2100 m3
Nylon vessels Inner 4.25 m Outer 5.50 m
20 legs
Design based on the principle of graded
shielding
Carbon steel plates
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Electron energy spectrum (05/08 - 10/08)
Neutrino spectrum - main components
493stat4syst counts/(day 100t) ?(7Be)(5.120.51
) x 1011 m2s1 SSM (5.080.5) x 1011 m2s1
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MSW - Vacuum transition
BOREXINO. First measurement of the ratio between
neutrino survival probability in vacuum and
matter Pee(7Be)/ Pee(8B)1.600.33
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??? and ?m2 next
MINOS - mainly ?? disappearance Fermi Lab to
Sudan (730 km) Improve precision on ?m2
OPERA - mainly ?e appearance CERN to LNGS (730
km) Prove ?? to ??
Cfr Prof. Parke
Cfr Prof. Coccia
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??? next
Accelerator experiments. ?e appearance MINOS
OPERA. Limited sensitivity near present
limit Near future (presumable starting dates,
many years more for final result) 2010. T2K
(Tokay to SuperK 300 km). Sensitivity ?132103
(if no event) 2015? NO?A (FNAL to Ash River, 820
km). Sensitivity ?132103 (if no event) sgn ?m2
Reactor experiments. ?e disappearance Optimum
distance for 1st maximum ? 2 km Sensitivity
dominated by systematic ? 1 sources (one source
group of ? 1 cores) ? 2 identical detectors
at different distances 2011. DoubleCHOOZ. 1
source 2 detectors _at_ ? 1 km. Sensitivity
?132102 2012 Daya Bay 3 sources 3 detectors
Sensitivity ?132 2x 103 2012? RENO 1 source 2
detectors, far _at_ 1.4 km
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Progress in ???
From M. Mezzetto, if no event observed
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Absolute neutrino masses
Effects O(m??/ E?)2 ?1020 _at_ E? 1 GeV ?1014 _at_
E? 1 MeV ?1 relic neutrinos (T 2K, Ekin ?
0.17 meV
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A cosmic connection
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Neutrino masses from cosmology
Neutrinos escape from structures, reducing the
amplitude of fluctuations at wave numbers (
Fourier conjugate of distance)
Power spectrum Fourier transform of mass
correlation function

• Crucial issue large structures (mass) power
  spectrum, determined by
• CMB spectrum at the largest scales
• WMAP-5 years data released astro-ph/0803.0547v2
• Galaxy power spectrum at intermediate scales
• Large volume galaxy surveys (2dFGRS SDSS)
• Ly-a forest at smaller scales
• Most sensitive length scale, but data inversion
  uncertain
• Limit on neutrino mass density ? limit on the sum
  of neutrino masses

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Limits on Neutrino Masses
Adapted from Goobar et al astro-ph/0602155
no effect on CMB fluctuations if ?m?ltTdecoupl?300
meV
PLANCK Gravit. lensing sensitivity ?m??150 meV
Planck ESA-SCI(2005) 1

• Caveats
• Set of basic parameters not uniquely defined
• We measure luminous mass, not total mass
  distributions
• Degeneracies between parameters

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Neutrino mass from beta decay
Tritium ? decay 3H ? 3He e ?e
Present limits ltmnegt lt 2.2 eV from Mainz and
Troitsk experiments
KATRIN (measurements in 2012) Limit _at_ ltmnegt gt200
meV Discovery (5?) _at_ ltmnegt 350 meV
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Majorana or Dirac particle?
SM neutrinos are massless, described by a
2-component (left) spinor If lepton number is not
conserved and if neutrinos are massive Neutrino
and antineutrino may be two states of the same
particle
NB. Neutrino propagator results in long-range
force
0nbb can happen, if beta decay is forbidden
1/t G(Q,Z) Mnucl2 Mee2
Majorana mass is a 3x3 matrix Mee is one of the
elements Cancellations are possible due to the
phase factors Mee0 does not imply neutrinos are
Dirac
Q is known for most nuclides within 104
uncertainty
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Majorana mass
Sensitivity of an experiment with background
index b, sensitive mass M, live time T and energy
resolution ?E
If b0 during T, in an energy window of about ?E
(a few keV for Ge and bolometers) sensitivity to
Mee? 2nd root of the exposure
The fraction of ???? events in ?E near end point
is
0??? signal/ 2??? background
Background free condition and and energy
resolution are the key features For Mee? 10 meV
need 1 t source mass AND b?? ?104 cts/(kg keV yr)
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Nuclear matrix elements

• Continuous progress in the nuclear matrix
  elements calculations in the last years
• Three methods
• Quasi Random Phase Approximation (QRPA)
• Shell Model (SM)
• Interacting Boson Model 2 (IBM2)

IBM-2 Barea Iachello 2009 QRPA Simkoich et al.
2008 ShM Courier et al. 2008

• Need understanding factor ?2 difference at small
  A
• Agree on a common case study with identical input
• Large uncertainty source Gamow-Teller coupling
  gA1.25? Quenched as in beta-decay?
• Appears as ga4 in the decay rate

116Cd
136Xe 150Nd 154Sm
76Ge
82Se
100Mo
128Te 130Te
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Compare nuclides
Matrix elements QRPA Tübingen Similar for
IBM2 Different if ScM
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The experimental challenge
Matrix elements QRPA Tübingen
Events per ton per year
KDKC claim
Mee500 meV
Mee50 meV
Mee15 meV
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Approved funded experiments
More in different stages of RD and apporval
(MOON, CARVEL, COBRA, DCBA, EXOgas, )
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Dark matter
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Neutralino SI cross sections

• Rates to be measured are proportional to the
  incoming WIMP flux local density rc times
  velocity (velocity distribution) ? halo-model
  dependent

R. Gaitskell, V. Mandic, J. Filippini
http//dendera.berkeley.edu/plotter/entryform.html
Spin Dependent (SI) coupling coherent scattering
? ??A2 Present expts not looking for
modulation Exposures 10 - 100 kg d Thresholds
7-5- keV Background few events
1 ev/(t d)
Lower limit from cosmology ? 6 GeV Lower limit
from LEP is on chargino, indirectly on
neutralino No firm theoretical upper limit on
the c mass (but reasonably lt 1000 GeV)
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Principles of WIMPs Detection

• Target Detector
• Measure the energy deposited by the hit nucleus
• Part of this energy appears as charge, light or
  heat
• Main challenges
• Signal rate is small
• Energy deposit is tiny (few keV)
• Signal spectrum decreases exponentially
• 3 basic backgrounds
• electromagnetic (b g) dominant ? electrons
• neutrons (and WIMPs) ? nuclear recoil
• surface contamination (partial energy release)

Against backgrounds Underground laboratory
Search for characteristic signal annual
modulation (DAMA/LIBRA) Passive shielding.
Against external backgrounds only Active
discrimination. Against external and internal
background Measure two quantities. Achieve event
by event rejection (as opposed to
statistical) Track images Tagging
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The Exclusion Plot

• First (classical) method
• Backgrounds cannot be accurately modelled and
  subtracted
• develop (aggressive) selection criteria to define
  a background-free region in the experimental
  parameters space
• Assume a halo model (local WIMP density,
  velocity,..)
• Calculate for each WIMP mass mc the maximum
  possible signal rate allowed by the data
• Result is model dependent

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The Counting Rate Modulation
Second method Signature for WIMPs interactions
Annual modulation of the rate. Earth velocity
relative to halo is maximum in June. Counting
rate expected to be in phase at high enough
recoil energies (ErecgtEX) (A. Drukier et al.
86 K. Freese et al. 88) A positive effect is
model independent
Picture from DAMA
Cosine law modulation of rate T1 year t0
June 21.3 days uorb/uSun ? 0.070.01?Amplitude
? 7 Only at lowest energies In only one detector
of the array
Positive evidence from DAMA - NaI scintillator -
250 kg _at_LNGS KIMS - CsI 100 kg running _at_ Y2L
(Korea) ANAIS - NaI 100 kg in construction _at_
LSC (Spain)
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Running/commissioning experiments
DAMA/LIBRA. Running at LNGS (Italy). 250 kg NaI
Scintillators KIMS. Running at Y2L (Korea). 100
kg CsI Scintillators CDMS II. Running at SUL
(USA). 4.75 kg Ge Bolometrs EDELWEISS II.
Running at LSM (France). 10 kg (40 kg foreseen)
Ge Bolometers CRESST2. Running at LNGS (Italy). 5
kg (10 kg foreseen) CaWO4 Bolometers XENON 100.
Running at LNGS (Italy). 170 kg Xe Liquid/Gas
TPC ZEPLIN II. Running at BUL (UK). 30 kg Xe
Liquid scintillation ZEPLIN III. Running at BUL
(UK). 5 kg Xe Liquid/Gas TPC WARP. Under
construction at LNGS (Italy). 140 kg Xe
Liquid/Gas TPC XMASS-100. Being installed in new
hall at Kamioka (Japan). 100 kg Xe Liquid
scintillation ArDM. Under test at LSC (Spain) 850
kg Xe Liquid/Gas TPC ANAIS. Under developement at
LSC (Spain) 100-150 kg NaI Scintillators COUPP.
Under development in FNAL (USA). Bubble chamber.
CF3Br
More in different stages of RD
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ArDM (LSC) XENON100
(LNGS)
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CDMS 5 towers
30 ZIP detectros 11 Si ZIPs (1.1 kg) 19 Ge (4.75
kg) On each detector 4 phonon sensors (recoil
energy) fast (µs) pulse shape determination 2
charge collectors (ionisation energy)
gs from source
ZIP technique detect phonons before complete
termalization ? discrimination of surface events
(g interactions in the electrodes give small
ionisation) Phonon start time and rise time
surface eventslt lt electron recoils lt nuclear
recoils Reduction factor 1/200
surface electrons
n from source
CDMS astro-ph/0802.3530
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CDMS. Results
120 kg d WIMP exposure No event in the signal
region after cuts Expected 0.60.5 backgrounds
Before ionisation timing cuts
After ionisation timing cuts
FUTURE. CDMS is still background free. Can gain
linearly with increasing exposure
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Noble Liquids one phase-two phases

• Noble liquids, Xe, Ar, and Ne look very
  promising for the WIMP detection, because
• can be easily assembled in large masses
• can be cleaned from radioactive traces at very
  high levels
• self-shielding structures can be built, with the
  central part shielded by a large contiguous mass
  (in the same container) of the same liquid ? no
  free surface, no surface contamination
• Shield can be instrumented to act as a veto

• Two-phase (Liquid Gas)
• discrimination between nuclear and
  electromagnetic recoils by
• detection of primary scintillation light and
  ionisation via proportional scintillation
  (Benetti et al. in 1993)
• difference in the time dependence of luminescence
  for light (slow component from 3S states) and
  heavy recoils (fast component from 1S states) (A.
  Hitachi et al. in 1983)

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Discrimination with Dual phase Xe/Ar

• Ionisation electrons discriminate ? high
  collection efficiency
• Eliminate of electronegative impurities lt 0.1 ppb
  
• Accurately design of the E field shape
• Efficient detection of primary light (? 200
  photons _at_ 16 keV in Xe)
• Localisation of event (to be in the fiducial
  volume)

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Discrimination with Dual phase Xe/Ar
Main background due to set-up components within
shields XENON100. Problem has been cured, running
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Present status (SI)
Comparisons are model dependent Tension between
DAMA and other experiments smaller below 10
GeV DAMA does not anti-select electromagnetic
background (or signal?)
CDMS
XENON-10
R. Gaitskell, V. Mandic, J. Filippini
http//dendera.berkeley.edu/plotter/entryform.html
43
In 10 years (SI)
RUNNING NOW
CDMS II
XENON100
WARP
LHC Help! Please
R. Gaitskell, V. Mandic, J. Filippini
http//dendera.berkeley.edu/plotter/entryform.html
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Direct Search of WIMPs
Assuming the muon g2 anomaly to be real and
due to SUSY
Baltz and Gondolo hep-ph/040739
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THANK YOU FOR YOUR ATTENTION
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The second cosmic ruler. The BAO
CMB acoustic oscillations _at_ z1089 Single peak in
baryon matter correlation function _at_?150h1 Mpc
(? 200 Mpc) Observed by SDSS _at_ z0.35 2 standard
rulers available at 2 epochs Distance between
the two epochs known _at_ 4 Confirms linear
cosmological perturbation theory across an
expansion factor 800 Removes degeneracy between
curvature and expansion rate
(Distance)2?correlation function
Curves are for different Wm
Astro-ph/0501171
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Small masses - large energies
Neutrino masses ltltltlt other fermions Indirect way
to look to the very high energy scales
Two independent phenomena point at the same high
energy scale
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Electron/nuclear recoil discrimination in Xe/Ar
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Two experimental approaches
very large sensitive mass demonstrated ? 50
kg proposed 1000 - 10000 kg per-mille energy
resolution Ge, bolometers only a few nuclides
Source detector Measure sum energy with
calorimetric techniques Ge semiconductor,
bolometers
low sensitive masses (few kg) poor energy
resolution several nuclides in the same
detector very good reconstruction of event
topology
NEMO III
Source ? detector Tracking (gas or liquid TPC,
drift chambers, etc) Magnetic field
Giuliani TAUP03
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The ultimate background 2b?n
Case of 136Xe assuming T1/2(????)?1021 (measured
lower limit)
High pressure TPC with Micromegas read out. Aim
EXO achieved
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Evidence from Heidelberg-Moscow _at_ LNGS
MT 10.9 kg (86 76Ge) x 13 yr b 0.11 ev/(kg
keV yr) before PSA Resolution on 8 years DE
3.27 keV
Claimed evidence of 0nbb _at_ 4s Mee 200-1000 meV
Expected position of 0nbb line well known Qbb
2039.0060.05 keV found _at_ Qbb 2038.70.44
(2.1 s)
IGEX _at_ LSC, the other experiment with Ge diodes
and similar sensitivity, gives an upper limit Mee
lt 0.33-1.3 eV no other experiment sensitive _at_
this level
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More dark theory
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Direct Search of WIMPs

• Look for WIMP-nucleus elastic scattering, detect
  energy deposited by recoiling nucleus
• Two kind of interactions of WIMPs with nuclei
• SD (spin dependent), axial vector coupling to
  nucleons spins only unpaired nucleons couple to
  WIMPs ? odd number of p or of n (J?0), ? J(J1)
• SI (spin independent), scalar interaction with
  the mass of the nucleus
• WIMP wavelength lt nuclear radius ? coherent
  process ? cross-section ? A2
• Coherence is lost at momentum transfer (Q) larger
  than the inverse nuclear radius (R) Qgt1/R?A1/3.
  Cross-section decreases
• Important for heavy targets
• Working at with high-Z (e.g. Xe) needs lower
  energy thresholds
• Important for heavy (several hundreds GeV) WIMPs

Loss of coherence is parametrised with a form
factor F(Q), which has roughly an exponential
behaviour
Use of form factors is a source of uncertainty
when comparing results on different nuclei Search
should be pursued with several different nuclei