Darkside: a Two Phases Argon Time Projection Chamber for Dark Matter Searches - Eugenio Paoloni
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Darkside:
a Two Phases Argon Time Projection
Chamber for Dark Matter Searches
Eugenio Paoloni,
INFN & Università di Pisa
Plan For this Tour de Force
➤ Why are we searching for Dark Matter?
➤ Astrophysical and cosmological evidences.
➤ Noble liquids Time Projection Chambers (TPC) for Dark
Matter search
➤ Prototypical example: Darkside 50
➤ Some neat features of Argon
➤ Backgrounds and backgrounds rejection
➤ Darkside 50 preliminary results
➤ Toward a multi tonne background free experiment:
Darkside 20k
2
Eugenio Paoloni INFN & Università di Pisa
Astrophysical Evidences
Zwicky Analysis of the Coma Cluster Dynamics
Fritz Zwicky,
(Varna 1898, Pasadena 1973)
Postulated the existence of Dark
Matter in 1930’s to explain the
dynamic behavior of the Coma
cluster
O(1000) galaxies. 46’ ~ 13 mRad
The Coma Cluster: Mosaic in false color (Red long waves infrared, Green short waves infrared, visibile light)
4
Eugenio Paoloni INFN & Università di Pisa
Put 1000 Galaxies on a Scale: Virial Theorem
➤ Zwicky and
Assuming that the theis held
Coma cluster Coma Cluste
together by classical
Zwicky and the Coma Cluster
gravitational forces and that it reached equilibrium, then
the
Forvirial theorem
systems states
in dynamical that for
equilibrium and a single
held galaxy
together of mass
by gravity, m: theorem
the virial
becomes: For systems in dynamical equilibrium and held together by gravity, the virial theorem
becomes:
1 21 MM
tot (r(r)m Velocities ~ 1000 km/
m(3 )m(3 2 ) G G tot )m Velocities ~ 1000 km/s
RR~~Mpcs
Mpcs
2 2 rr Distance~100~100
Distance MpcMpc
2hT i2hT
=i =hVhV
ii (1pcpc==3.26
(1 3.26 light
light yrs)yrs)
By measuringBy measuring the velocity
the velocity (dispersion)
(dispersion) of theof the galaxiesininthe
galaxies the Coma
Coma cluster, Zwicky
cluster, could
Zwicky cou
➤ Byinfer its total mass. velocity dispersion σ (Doppler shift) and
measuring infer itsthe
total mass.
However, the luminous mass (the galaxies in the cluster) was far smaller!
the distance
However, r from mass
the luminous the cluster center
(the galaxies in theZwicky
cluster) was
F. Zwicky, Astrophysical Journal, vol. 86, p.217 (1937)
was farable to
smaller!
measure
F. Zwicky,M tot, ie. the
Astrophysical total
Journal, mass
vol. 86, of the cluster
p.217 (1937)
s
star gas
DM s
star g
DM
5
Eugenio Paoloni INFN & Università di Pisa
1937ApJ....86..21
F. Zwicky, Astrophysical Journal, vol. 86, p.217 (1937)
[…]
[…]
6
Eugenio Paoloni INFN & Università di Pisa
Rotation Curves of Galaxies
➤ Measure line of sight velocity of stars and gas via Doppler
shift (Hα in optical and HI 21 cm line in radio)
Galaxies
Infer the tangential velocity, apply classical mechanics
➤
M31 ( Andromeda )
Image of the Andromeda galaxy (M31)
(2007) with rotation curve superimposed (Turner,2000)
7
Eugenio Paoloni INFN & Università di Pisa
NGC 3198
8.5
’~
2.5
m
Ra
d
NGC 3198: 14 Mpc, Visual Magnitude 9.15
8
Eugenio Paoloni INFN & Università di Pisa
⇠ 25 kpc, also this modified baryon ⇤CDM halo profile appears to create a tension with the derived DM halo density.
[astro-ph. Key words.
Astronomy Dark Matter;
& Astrophysics
April 13, 2015
Galaxy:
manuscript NGC 3198; NFW haloes; Universal Rotation Curve; Baryonic Feedback
no. N3198A_A2col c ESO 2015
1. Introduction and HI-21 cm radio observations (Bosma 1981; van Albada et al.
1985; Begeman 1987, the latter established it as the object with
It has been known for several decades that the kinematics of disk the clearest evidence for DM), see also (de Blok et al. 2008;
The leads
galaxies darkto mattera mass discrepancydistribution (e.g. Bosma in1978;the Bosma
spiral Gentile NGC2008). 3198 out to 0.22 Rvir
arXiv:1503.04049v2
& van der Kruit 1979; Rubin etE.V. al. Karukes
1980). 1,While in their
2 , P. Salucci in- G. Gentile
1, 2 and Our3, 4present analysis is mainly based on the HI observations
ner regions that range between one and threeA&A disk proofs:
exponentialmanuscriptby Gentile et al. (2013), part of the HALOGAS (Westerbork Hy-
no. N3198A_A2col
scale lengths
1 according
SISSA/ISAS, to the
International galaxy
School luminosity
for Advanced Studies,(Salucci & Per-
Via Bonomea drogen
265, 34136, Trieste,Accretion
Italy in LOcal GAlaxieS) survey. The main goal
sic 1999),
2
observed baryonic matter accounts for the rotation of HALOGAS is to investigate the amount and properties of
the ekarukes@sissa.it
e-mail:
INFN, Sezione
(e.g. diAthanassoula
Trieste, Via Valerio et2,al.
34127, Trieste, Italy & Salucci extra-planar gas by using very deep HI observations. In fact, for
curves3 (RCs) 200 1987; Persic
Department of Physics and Astrophysics, Vrije Universiteit Brussel, Pleinlaan 2, 1050 Brussels, Belgium
1988; 4Palunas & Williams
Sterrenkundig Observatorium, 2000), we must
Universiteit add an281,
Gent, Krijgslaan extra mass
B-9000 this galaxy, they present a very extended RC out to 720 arc-
Gent, Belgium
component in the outer regions, namely a dark matter (DM) halo sec, corresponding to ⇠ 48 kpc for a galaxy distance at 13.8
April 13, 2015
to account for that component. The kinematics of spirals is now Mpc (Freedman et al. 2001). The previous HI observations by
In de Blok et al. (2008) were only extended out to ⇠ 38 kpc, for
Apr 2015
routinely interpreted in the framework of a DM component.
the widely accepted Lambda 150 cold dark matter (⇤CDM) scenario, the same galaxy distance. In Gentile et al. (2013) this extended
ABSTRACT
the virialized
Aims. We structures
use recent very are distributed
extended according
HI kinematics (out to 48thekpc)
well known
along RCH↵was
with previous modelled
kinematics in thegalaxy
of the spiral framework
NGC 3198 of modified Newtonian dy-
in order to derive its distribution of dark matter (DM). namics (MOND). Here, we want to use such a uniquely extended
NFW Methods.
profile proposed
First, we usedby Navarro,method Frenk, and White (Navarro
V Hkm s-1 L
a chi-square to model the rotation curve (RC) of this galaxy in terms of di↵erent profiles of its
et al. 1996). The ⇤CDM
DM distribution: scenario
the universal rotationdescribes
curve (URC) the
masslarge-scale struc-
model (stellar kinematics
disk + Burkert to help
halo + gaseous resolving
disk), the NFW massthe model
DM core-cusp issue. To the very
ture of(stellar
the Universe
disk + NFWwell halo +(e.g. Springel
gaseous disk) and et
theal. 2006),
baryon ⇤CDM but it seems
mass reliable
model (stellar disk + NFWkinematics
halo modified available
by baryonicfrom 2 to 48 kpc we apply two dif-
physics
+ gaseous disk). Second, 100 to derive the DM halo density distribution, we applied a new method that does not require a global and often
of galaxies (de Blok & Bosma 2002; Gen- ferent mass decomposition methods that will derive the DM halo
03.04049v2 [astro-ph.GA] 10
to failuncertain
on the massscales
modelling.
tile et Results.
al. 2004,While2005).
accordingGoing into detail,
to the standard method,the bothNFW
URC and density
NFW mass pro-modelsstructure.
can account This
for the is
RC,compared
the new method with a) the empirically based halo
instead
leads to
file leads to athe
density profile that isproblem”:
“core-cusp sharply disagrees with the dark
empirical halo density
profiles a profiles
withdistribution coming
predicted within the from
Lambda thecoldURC, b) the NFW haloes and c) the
dark matter
(⇤CDM) scenario. We find that the e↵ects of baryonic physics modify the original ⇤CDM halo densities in such a way that the
centralresulting
core of constant
profile density, with
is more compatible such the as
DMthe pseudo-isothermal
density of NGC 3198 derived using baryon
our new⇤CDM haloes,atthe
method. However, largeoutcome
distances, r of Corradi
scenarios in which bary-
(Begeman et also
⇠ 25 kpc, al. this
1991; Kent
50baryon
modified 1986)⇤CDM andhalothe Burkert
profile appears(Salucci & onic
to create a tension physics
with the derived DM hashalo
shaped
density.the DM halo density.
Burkert Key2000),
words. fitDark the available
Matter; Galaxy: RCs much
NGC 3198; NFWbetter
haloes; than the mass
Universal Rotation Curve;This paper
Baryonic is organized as follows. Daigle
Feedback In Sect. 2 we present the
models based on NFW haloes. HI and H↵ kinematics used in this study. In Sect. 3 we model
Gentile
In the present paper, we derive the DM content and distri- the RC by using the quadrature sum of the contributions of the
1. Introduction
bution in the spiral galaxy NGC 3198. This galaxy has been and HI-21
the cmindividual
radio observations
mass (Bosma
components1981; van Albadadisk
(stellar et al.+ dark halo + gas disk)
subject of several investigations. 0 It was studied by means1985; of Begeman 1987, the latter established it as the object with
opti- where the dark halo has a NFW or a Burkert density profile,
It has been known for several decades 0 that the kinematics 10 of disk the clearest 20 evidence for DM), see also (de Blok et al. 2008;
30Sect. 4 we obtain 40the results of standard
50
HkpcL
cal (Cheriguène 1975; Hunter et al. 1986; Bottema 1988; Wevers respectively. In
galaxies leads to a mass discrepancy (e.g. Bosma 1978; Bosma Gentile 2008).
mass
et&al.van1986; Kent1979;
der Kruit 1987; Corradi
Rubin et al. 1991;
et al. 1980). While inDaigletheir in- et al. 2006)
Our presentmodelling
analysis is of the NGC
mainly based on 3198 RC.
the HI In Sect. 5 we use a recent mass
observations
ner regions that range between one and three disk exponential by Gentile et al. r (2013), part of the HALOGAS (Westerbork Hy-
scale lengths according to the galaxy luminosity (Salucci & Per- drogen Accretion in LOcal Article number, page 1 of 10
GAlaxieS) survey. The main goal
Fig. 1. sic
Comparison between
1999), the observed H↵ and
baryonic matterHI RCs black
accounts for the open of HALOGAS is to investigate the amount and properties
rotationtriangles with error bars from Corradi et al. (1991), blue of circles with error bars are from
(RCs) (e.g. Athanassoula et al. 1987; Persic & Salucci extra-planar gas by using very deep HI observations. In fact, for
Daigle curves
et al. (2006), and red circles with error bars are from Gentile et al. (2013).
1988; Palunas & Williams 2000), we must add an extra mass this galaxy, they present a very extended RC out to 720 arc-
component in the outer regions, namely a dark matter (DM) halo sec, corresponding to ⇠ 48 kpc for a galaxy distance at 13.8
to account for that component. The kinematics of spirals is now Mpc (Freedman et al. 2001). The previous HI observations by
9
Eugenio de Paoloni INFN
Blok et &Table
Università
al. (2008) 1. only
were diextended
Stellar Pisa
disk out to ⇠ 38 kpc,Vfor(km s 1 ) (de Blok et al. 2008) and
contribution
NGC 3198 components E.V. Karukes et al.: The dark matter distribution in the spiral NGC 3198 out to 0.22 Rvir
10-22
10-23
Rotation Curves of Galaxies
reff Hgêcm3 L
10-24
From newtonian dynamics:
-25
2 10
mv mM
F = =G 2
r -26
r
10
1/2 NGC 2403
v(r) / r
For constant 10
v: -27
Rotation Curves of Ga
0 10 20 30 40 50
r HkpcL
2
M (r) / r ⇢(r) / r From newtonian Corbelli
dynamics:et al (2009)
Mass density not as steeply falling as star 2 M31
Fig. 7. Density profile of the DM halo of NGC 3198 and the e↵ective density mv
of the other mM
components. We assume M 10
D = 4.4 ⇥ 10 M . The
density (exponential)!
stellar disk (Blue line), the HI disk (magenta line), the dark halo (red line)Fand
=the sum of = G
all components (green line). The di↵erent colour regions
r Darkr 2matter
correspond to the regions a) where we do not have any kinematical information due to the lack of data (dark purple), b) where the stellar disk
➡ By adding extended dark matter halo
dominates the DM density profile (light purple) and c) where DM dominates (white). Stellar disk
get good fit to the data. v(r) / r 1/2
Stellar bulge
Similar exercise for the Milky Way yields For constant v: Gas
local DM density: 2
ρ(8.5 kpc)~0.2-0.5 GeV/cm3 (direct Údetection) M (r) / r ⇢(r) / r
Ú
10-24 Ú Ú
Ú MassÚ
density not as steeply falling as star
Ú
densityÚ &(exponential)!
10
Eugenio Paoloni ÚINFN Università di PisaThe Bullet Cluster Smoking Gun Evidence
The Astrophysical Journal, 604:596–603, 2004 April 1
# 2004. The American Astronomical Society. All rights reserved. Printed in U.S.A.
WEAK-LENSING MASS RECONSTRUCTION OF THE INTERACTING CLUSTER 1E 0657!558:
DIRECT EVIDENCE FOR THE EXISTENCE OF DARK MATTER1
Douglas Clowe2
1.1 Gpc (3.7 Gly)
Institut für Astrophysik und Extraterrestrische Forschung der Universität Bonn, Auf dem Hügel 71, 53121 Bonn, Germany; dclowe@as.arizona.edu
Anthony Gonzalez
Department of Astronomy, University of Florida, 211 Bryant Space Science Center, Gainesville, FL 32611-2055
and
Maxim Markevitch
Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138
Received 2003 October 28; accepted 2003 December 11
ABSTRACT
We present a weak-lensing mass reconstruction of the interacting cluster 1E 0657!558, in which we detect
both the main cluster and a subcluster. The subcluster is identified as a smaller cluster that has just undergone
initial infall and pass-through of the primary cluster and has been previously identified in both optical surveys
and X-ray studies. The X-ray gas has been separated from the galaxies by ram pressure–stripping during the
pass-through. The detected mass peak is located between the X-ray peak and galaxy concentration, although the
position is consistent with the galaxy centroid within the errors of the mass reconstruction. We find that the mass
peak for the main cluster is in good spatial agreement with the cluster galaxies and is offset from the X-ray halo at
3.4 ! significance, and we determine that the mass-to-light ratios of the two components are consistent with those
of relaxed clusters. The observed offsets of the lensing mass peaks from the peaks of the dominant visible mass
X-ray photo (140
proof of dark hr)existence holds
component (the X-ray gas) directly demonstrate the presence, and dominance, of dark matter in this cluster. This
matter 0.45 mRad
true even under the assumption of modified Newtonian dynamics (MOND);
based on the observed gravitational shear–optical light ratios and the mass peak–X-ray gas offsets, the dark
matter component in a MOND regime would have a total mass that is at least equal to the baryonic mass of the
system.
11
Subject headings: dark matter — galaxies:Eugenio Paoloni individual
clusters: INFN & Università di Pisa — gravitational lensing
(1E 0657!556)Superimposing the 2 Pictures
Co
Ho lli
sio
tc n-
Co ol les
lli lid s
sio in DM
n- gg
les as
s
DM
12
Eugenio Paoloni INFN & Università di PisaDark Matter Ring
The ring, 2.6-million light-years wide,
formed when two huge clusters of
galaxies slammed together in a head-on
collision 6 to 7 billion years ago,
puffing the mysterious matter outward,
the astronomers figure. If the galactic
hit-and-run had occurred outside of
Earth's line-of-sight, the result might
look more like the "Bullet cluster"--
another cosmic impact site that
astronomers view as strong evidence for
dark matter. (from NBC news)
14
Eugenio Paoloni INFN & Università di PisaCosmology (From Astrophysical Observation)
Nine-Year Wilkinson Microwave Anisotropy Probe (WMAP)
Observations: Final Maps and Results
Sky in different microwaves bands
C. L. Bennett1 , D. Larson1 , J. L. Weiland1 , N. Jarosik2 , G. Hinshaw3 , N. Odegard4 , K. M.
Smith5,6 , R. S. Hill4 , B. Gold7 , M. Halpern3 , E. Komatsu8,9,10 , M. R. Nolta11 , L. Page2 , D.
N. Spergel6,9 , E. Wollack12 , J. Dunkley13 , A. Kogut12 , M. Limon14 , S. S. Meyer15 , G. S.
Tucker16 , E. L. Wright17
cbennett@jhu.edu
ABSTRACT
1
Dept. of Physics & Astronomy, The Johns Hopkins University, 3400 N. Charles St., Baltimore, MD
21218-2686
2
Dept. of Physics, Jadwin Hall, Princeton University, Princeton, NJ 08544-0708
3
Dept. of Physics and Astronomy, University of British Columbia, Vancouver, BC Canada V6T 1Z1
4
ADNET Systems, Inc., 7515 Mission Dr., Suite A100 Lanham, Maryland 20706
5
Perimeter Institute for Theoretical Physics, Waterloo, ON N2L 2Y5, Canada
6
Dept. of Astrophysical Sciences, Peyton Hall, Princeton University, Princeton, NJ 08544-1001
7
University of Minnesota, School of Physics & Astronomy, 116 Church Street S.E., Minneapolis, MN
55455
Backgrounds to subtract
8
Max-Planck-Institut für Astrophysik, Karl-Schwarzschild Str. 1, 85741 Garching, Germany
9
Kavli Institute for the Physics and Mathematics of the Universe, Todai Institutes for Advanced Study,
the University of Tokyo, Kashiwa, Japan 277-8583 (Kavli IPMU, WPI)
10
Texas Cosmology Center and Dept. of Astronomy, Univ. of Texas, Austin, 2511 Speedway, RLM 15.306, 15
Eugenio Paoloni INFN & Università di PisaTemperature Fluctuations of The Early Universe As Seen Now
WMAP (NASA). Temperature Range +/- 200 μK
16
Eugenio Paoloni INFN & Università di Pisaspherical harmonics
Angular Correlations of The Temperature Fluctuations
TT
T T
TT
T T
NASA / WMAP Scienc
Fig. 32.— The nine-year WMAP TT angular power spectrum. The WMAP data are in
black, with error bars, the best fit model is the red curve, and the smoothed binned cosmic
variance curve is the shaded region. The first three acoustic peaks are well-determined.
17
Eugenio Paoloni INFN & Università di PisaCosmological Parameter Summary
Table 17. Cosmological Parameter Summary ( PDG )
Parameter Symbol WMAP a WMAP+eCMB+BAO+H0 a b
6-parameter ΛCDM fit parametersc
Physical baryon density Ωb h2 0.02264 ± 0.00050 0.02223 ± 0.00033
Physical cold dark matter density Ωc h2 0.1138 ± 0.0045 0.1153 ± 0.0019
Dark energy density (w = −1) ΩΛ 0.721 ± 0.025 0.7135+0.0095
−0.0096
−1
Curvature perturbations (k0 = 0.002 Mpc ) d 109 ∆2R 2.41 ± 0.10 2.464 ± 0.072
Scalar spectral index ns 0.972 ± 0.013 0.9608 ± 0.0080
Reionization optical depth τ 0.089 ± 0.014 0.081 ± 0.012
Amplitude of SZ power spectrum template ASZ < 2.0 (95% CL) < 1.0 (95% CL)
6-parameter ΛCDM fit: derived parameterse
Age of the universe (Gyr) t0 13.74 ± 0.11 13.772 ± 0.059
Hubble parameter, H0 = 100h km/s/Mpc H0 70.0 ± 2.2 69.32 ± 0.80
Density fluctuations @ 8h−1 Mpc σ8 0.821 ± 0.023 0.820+0.013
−0.014
Velocity fluctuations @ 8h−1 Mpc σ8 Ω0.5
m 0.434 ± 0.029 0.439 ± 0.012
Velocity fluctuations @ 8h−1 Mpc σ8 Ω0.6
m 0.382 ± 0.029 0.387 ± 0.012
Baryon density/critical density Ωb 0.0463 ± 0.0024 0.04628 ± 0.00093
Cold dark matter density/critical density Ωc – 130 –0.233 ± 0.023 0.2402+0.0088
−0.0087
+0.0096
Matter density/critical density (Ωc + Ωb ) Ωm 0.279 ± 0.025 0.2865−0.0095
Physical matter density Ωm h2 0.1364 ± 0.0044 0.1376 ± 0.0020
Current baryon density (cm−3 )f nb (2.542 ± 0.056) × 10−7 (2.497 ± 0.037) × 10−7
Current photon density (cm−3 )g nγ 410.72 ± 0.26 410.72 ± 0.26
Baryon/photon ratio η (6.19 ± 0.14) × 10−10 (6.079 ± 0.090) × 10−10
Redshift of matter-radiation equality Table
zeq 17—Continued
3265+106
−105 3293 ± 47
Angular diameter distance to zeq (Mpc) dA (zeq ) 14194 ± 117 14173+66
−65
Horizon scale at zeq (h/Mpc) keq 0.00996 ± 0.00032 0.01004 ± 0.00014
Parameter Symbol WMAP a WMAP+eCMB+BAO+H0 a b
Angular horizon scale at zeq leq 139.7 ± 3.5 140.7 ± 1.4
Tensor spectral indexl
Epoch of photon decoupling zn∗t > 1090.97
−0.048+0.85
(95% CL)
−0.86
> −0.016
1091.64 ± 0.47 (95% CL)
+0.044 +0.0039
Curvature
Age at photon(1 − Ωtot )m(yr)
decoupling tΩ∗k −0.037
376371 +4115
−0.042 374935−0.0027
+1731
−0.0038
−4111 −1729
Fractional
Angular Helium
diameter abundance,
distance by hmass
to z∗ (Mpc) dYAHe(z∗ )Ok… let’s say that DM exists,
what
the heck is it anyhow ???What we Do Know After an 80 Years Long Investigation?
:` +B2H :2HKBMB@l*G
7i2` 3y v2 `b- r? i r2 FMQr #Qmi .J,
̫ ii` +iBp2 ;` pBi iBQM H BMi2` +iBQMb M/ bi #H2 UQ` HB72iBK2 ॺॢ V
̫ .J M/ MQi JPL. Y QMHv pBbB#H2 K ii2` Udz"mHH2i *Hmbi2`ǴV
̫ RyХ :2o ѷK bbѷRyХJҬ Ry:2o UHBKBib QM J*>Pa bi`Q@T?fyeydkydV
Udz6mxxv .JǴ- #QbQM /2 "`Q;HB2 r p2H2M;i?4 R FT+ >m- " `F M - :`mxBMQp- bi`Q@T?fyyyjje8V
Q` yXk@yXd ƓRyХ :2oѷ K bb U7Q` T `iB+H2b r?B+? `2 +?2/ 2[mBHB#`BmK @ /2T2M/BM; QM
#QbQM@72`KBQM M/ /XQX7X h`2K BM2@:mMM RNdNc J /b2M- bi`Q@T?fyyyeyd9V
.J T `iB+H2 K bb, 3y Q`/2`b Q7 K ;MBim/25
GL:a- P+iQ#2` kR- kyR9 e 20
Eugenio Paoloni INFN & Università di PisaHopefully DM Interacts with Ordinary Matte
KIS (Keep It Simple)/
Occam’s Razor:
WIMP - Nucleus
Elastic Collision
40
Ar Kin En (keV)
Max Transferred Energy
Ar 150
WIMP
100
Ar
WIMP
50
DM Mass (GeV)
1 10 100 1000 104
Use neutrons to mimic
WIMPs
for calibrations 21
Eugenio Paoloni INFN & Università di PisaTwo Phases Time Projection Chamber (Darkside 50)
Electric
Field: Multipl.
(4200 V/cm)
Electric
Field: Drift
(200 V/cm)
22
Eugenio Paoloni INFN & Università di PisaThe Prompt Signal
~ 40 primary photons UV (128nm) / keV 23
Eugenio Paoloni INFN & Università di PisaThe Delayed Signal
24
Eugenio Paoloni INFN & Università di PisaThe Darkside PMT array and the whole TPC
25
Eugenio Paoloni INFN & Università di PisaBackgrounds
➤ We are looking for extremely rare events consisting of a few
10s of keV released in the detector, that is a few tens of
photons on the PMT
➤ The signal must come out of the blue in the core of the
detector
➤ radioactive decays inside the detector Clean Construction
➤ neutrons ( cosmogenic, radiogenic )
Shielding+Veto +
➤ γ rays Background
rejection
➤ neutrino - electron scattering
➤ neutrino floor (coherent neutrino - nucleus scattering)
26
Eugenio Paoloni INFN & Università di PisaBackgrounds [30-200] keVr
Backgrounds
NUCLEAR
ELECTRON
RECOILS
RECOILS
μ
n
39Ar n ~30 evt/m2/day
~9x104 evt/kg/day α 39Ar
μ Radiogenic n
γ ~6x10-4 evt/kg/day
γ
~1x102 evt/kg/day α
γ ~10 evt/m2/day
100 GeV, 10-45cm2 WIMP Rate ~ 10-4 evt/kg/day
07/03/16 - Les Rencontres de Physique de la Vallée d'Aoste D. D'Angelo - The DarkSide physics program and its recent results 27
27
Eugenio Paoloni INFN & Università di PisaDarkside 50 Vetos Systems
DarkSide-50
Housed in CTF
Borexino CounLng Test Facility
Radon-free (Rn levels < 5 mBq/m3)
Clean Room
1,000-tonne Water-based
Cherenkov Cosmic Ray Veto
30-tonne Liquid ScinLllator
Neutron and γ’s Veto
Inner detector TPC
07/03/16 - Les Rencontres de Physique de la Vallée d'Aoste D. D'Angelo - The DarkSide physics program and its recent results 5
28
Eugenio Paoloni INFN & Università di Pisaa s s o
Gr an S
Under 3800 meters
of equivalent water
shield in
LNGSPulse Shape Discrimina8on
Electron
Pulse and nuclear
Shape
Electron recoils
Discrimination
and nuclear produce
recoils different
produce different excitaLon
excitaLon densiLes
densiLes in the argo
in the argon,
leading to different
leading ra8os
to different of of
ra8os singlet
singlet and triplet
and triplet excita8on
excita8on states states
τsinglet ~ 7 ns
τsinglet ~ 7 ns
τtriplet ~ 1500 ns
τtriplet ~ 1500 ns
Electron Recoil
Electron Recoil
Averaged Wave forms
Nuclear Recoil
Averaged Wave fo
07/03/16 - Les Rencontres de Physique de la Vallée d'Aoste D. D'Angelo - The DarkSide physics program and its recent results 8
Nuclear Recoil Different singlet/triplet excitations ratio.
Electron recoil pulse shape is longer
30
Eugenio
07/03/16 - Les Rencontres de Physique de Paoloni
la Vallée INFN & Università
d'Aoste D. di Pisa - The DarkSide physics program and its recent results
D'Angelo(663 keV) 137Cs
Calibration
•
And Cross-checks
CALIS
Neutron source: AmBe
CALibraLon
CALISInserLon System
CALibraLon InserLon System
Calibrate both TPC and Neutron veto
Calibrate
• both TPC
Gamma and Neutron
sources: vetokeV), 133Ba (356 keV),
57Co (122 NR band matches with the points extr
• Gamma sources: 57Co (122 keV), 133Ba (356 keV),
137Cs (663 keV)
137Cs (663 keV)
•• Neutron
Neutron source:
source: AmBeAmBe NR study (crosscheck of SCENE data)
NR band matches with the points extrapolated from SCENE.
NR band matches with the points extrapolated from SCENE.
NR study (crosscheck of SCENE data) Test of the MC code
NR study (crosscheck of SCENE data) Test of the MC code
NR band Signal Band
NR band
NR band
ER band
ER band
ER band Bkg. Band
07/03/16 - Les Rencontres de Physique de la Vallée d'Aoste D. D'Angelo - The DarkSide physics program and its recent results 15
07/03/16 - Les Rencontres de Physique de la Vallée d'Aoste D. D'Angelo - The DarkSide physics program and its recent results 3115
Eugenio Paoloni INFN & Università di PisaArgon Isotopical Composition
➤ 39Ar (Cosmogenic Isotope ) is a
contaminant of Argon extracted from
atmosphere
➤ β emitter
(565 keV head of the spectrum)
darkside 50
➤ Intrinsic radioactivity 1Bq/kg
➤ Limiting factor for multi ton detectors S2
e-
➤ The activity of Argon from the deep
underground CO2 mine in Colorado is S1
~ 150 times lower
➤ Distillation plant produces 0.5 kg/d of
underground Argon (uAr) WIMP
32
Eugenio Paoloni INFN & Università di PisaUnderground Ar
1. Extrac8on at Colorado (CO2 Well)
Extract a crude argon gas mixture (Ar, N2, and
He)
Plant at Colorado
2. Purifica8on at Fermilab
Separate Ar from He and N2
DisLllaLon Column at
Fermilab
3. Arrived at LNGS
UAr boSles at LNGS Ready to fill into DS-50
07/03/16 - Les Rencontres de Physique de la Vallée d'Aoste D. D'Angelo - The DarkSide physics program and its recent results 18UAr vs Atmospheric
UArArgon
First(AAr)
Results
AAr vs UAr. Live-Lme-normalized S1 pulse integral spectra at Zero field.
10−1
Events / [50 PE × kg × s]
AAr Data UAr Data
39
MC Total Ar
10−2 85
Kr 238
U Cryostat
~1/1400 238
U Fused Silica 232
Th Cryostat
232 232
Th Fused Silica Th PMT Stem
−3
10 ~1/300 60
Co Cryostat 40
K PMT Photocathode
235 222
U PMT Stem Rn TPC
54
−4 Mn PMT Stem
10
10−5
10−6
10−7
10−8 0 2000 4000 6000 8000 10000 12000 14000 16000 18000 20000
S1 [PE]
Low level of 39Ar allows extension of DarkSide program to ton-scale detector.
07/03/16 - Les Rencontres de Physique de la Vallée d'Aoste D. D'Angelo - The DarkSide physics program and its recent results
34 19
Eugenio Paoloni INFN & Università di PisaDarkside with Underground Argon First results
UAr First Results
No background events in nuclear recoil (WIMP) region!
WIMP Expected Region
71 live-days aher all cuts. (2616±43) kg day exposure.
Single-hit interacLons in the TPC, no energy deposiLon in the veto arXiv:1510.00702
07/03/16 - Les Rencontres de Physique de la Vallée d'Aoste D. D'Angelo - The DarkSide physics program and its recent results 20
35
Eugenio Paoloni INFN & Università di PisaDarkside 50 Exclusion
σ [cm 2]
Region
UAr First Results
01 4)
2
−42 AA r,
10 - 50
(
5)
d e 01
WARP (2007)
arkSi r, 2 d)
1) D (U A ne
01 0 b i
(2 d e -5 ( com
I
I N-II ar kSi e-50
L D id
−43 ZEP k S
10 )
Dar
5
( 201
O
PIC
CDMS (2015)
10−44
PandaX-I (2015)
12)
0 (20
0
ON1
XEN
5)
10−45 U X (2 0 1
L
10 102 103 104
Mχ [GeV/c2]
Best limit to date, with argon target, third best limit behind LUX & Xenon100.
07/03/16 - Les Rencontres de Physique de la Vallée d'Aoste D. D'Angelo - The DarkSide physics program and its recent results 21
36
Eugenio Paoloni INFN & Università di PisaSiPM
Ok…
What Next?
SiPMFuture Searches using 2 phases Argon TPC
Expected sensi8vity
➤ Longer exposure, then larger detector
10−41
σ [cm 2]
)
(2007 )
W A R P
O (2015
10−42 P I C
2 014 )
I ( 15)
Pan daX- (2 0
10−43 ide-50
DarkS )
yr proj.
CDMS ) e - 50 (3
10−44 (2015) 1 0 0 (2012 DarkS
i d
XEN ON
2013 )
−45 (
10 L U X
10−46 )
y r proj.
k ( 1 00 t
10−47 k S i d e-20
Dar oj.)
y r p r
( 1 0 00 t
10−48 Argo
10−49
10−50
10 102 103 104
M χ [GeV/c2]
07/03/16 - Les Rencontres de Physique de la Vallée d'Aoste D. D'Angelo - The DarkSide physics program and its recent results 3824
Eugenio Paoloni INFN & Università di PisaDarkside Past, Present, Future
➤ 2010-2012; DS-10 at Princeton-> LNGS 10 kg normal Ar not radiopure, water-block
shielding, 8 PMTs
➤ 2013-present; DS-50 at LNGS
153 kg total, 36.9 kg fiducial
radiopure construction, UAr target (arXiv 1204.6024; see below) high efficiency
neutron shield/veto
currently: > 4000 kg-day analyzed, planned exposure 3 years
-44
8.6x10 cm2 @ 1 TeV/c2, world's 3rd best current limit
➤ ~2020 DS-20k at LNGS (proposed to NSF & INFN 2015)
30 ton total, 20 ton fiducial
radiopure construction, Depleted Ar target, SiPM sensors high efficiency neutron
shield/veto
-47 -46
100 ton-year planned exposure 10 (10 ) cm2 at 1(10) Tev/c2
➤ 202x ARGO at LNGS
1000 ton-year planned exposure
to reach the solar ν coherent scattering floor detailed solar ν studies possible
(arXiv 1510.04196)
39
Eugenio Paoloni INFN & Università di PisaToward a MultiTonne Background Free 2 Phases Ar TPC
➤ Background free:
➤ Darkside 50 collected 47.1 live days (1422 kg x day fiducial) of Atmospheric Argon
data
➤ The sample corresponds to the expected background of
180 live years of UAr operations
39
➤ Darkside demonstrated complete background rejection of Ar bkg. at level of 5.5
ton x year
➤ Project Urania (Underground Argon):
➤ Expansion of the argon extraction plant in Cortez, CO, to reach capacity of 100
kg/day of UArg
➤ Project Aria (UAr Purification):
➤ 100s meters tall distillation column in the Seruci mine (Sardinia) for further
reduction of UAr contaminants
➤ First test facility funded by INFN, Sardinia regional funds for the construction of
the complete facility
40
Eugenio Paoloni INFN & Università di PisaPhoto sensors
➤ Replace PMT with SiPM
➤ Pros:
➤ Cheaper
➤ More efficient
(filling factor)
➤ More radiopure
➤ Cons:
➤ 15 m2 of SiPM arrays: hundred thousands of devices
➤ Cold front end electronic to sum SiPM output
➤ Intense R/D ongoing
41
Eugenio Paoloni INFN & Università di PisaSiPM At Cryogenic Temperature
Big R&D News- Can
Dark Rate at 87 be
K Quie
42
Eugenio Paoloni INFN & Università di PisaConclusions
➤ I tried to cover lot of material today
➤ The astrophysical and cosmological evidences of the
existence of Dark Matter together with an estimate of the
local density
➤ The concept of 2 phases noble gas TPC for DM searches
➤ The main characteristics of a prototypical TPC: Darkside
➤ The latest results from Darkside
➤ The plans for the next generation of Darkside
➤ I hope you survived the tour de force
43
Eugenio Paoloni INFN & Università di Pisas of galactic rotation curves, but seem to run into conflict with the results of
e and collaborators [41].
a convergent determination
DM halo profiles
ations. On the other hand, profiles steeper that NFW had been previously
Angle fromofthethe
GCactual
degrees⇥DM profile is not reached, it is
From N-body numerical simulations:
t disposal10the30⇤⇤whole range
5⇤ 10⇤ of
30⇤ these
1o 2o possible
5o 10o20o45choices when computing Dark
⇤⇤
1⇤ o
n the Milky Way. The functional forms of these profiles read:
104 Moore
⇤ ⌅ 2
3
10NFW :NFW
r s r DM halo r s [kpc] ⇥ s [GeV/cm 3
]
⇥NFW (r) = ⇥s 1+
⇥DM GeV⇤cm3 ⇥
Einasto
r
EinastoB
rs
102 ⌥ ⇧⇤ ⌅ ⌃ NFW 24.42 0.184
2 r
Einasto
10
: ⇥Ein (r) = ⇥s exp 1 Einasto 0.17 28.44 0.033
rs EinastoB 0.11 35.24 0.021
Iso ⇥
1
Isothermal : ⇥Iso (r) =
s
2
Isothermal(1) 4.38 1.387
⇥ Burkert
1 + (r/rs )
10 1 Burkert 12.67 0.712
⇥s
Burkert : ⇥Bur (r) = r 2
Moore 30.28 0.105
10 2 (1 + r/rs )(1 + (r/rs ) )
⇤ 10 ⌅ 1.84 2
10 3 10 2 10 1 rs ⇥1.16 1 r 10 Angle from the GC degrees⇥
Moore : ⇥Moo (r) = ⇥s 1+
r kpc⇥r rs 10⇤⇤ 30⇤⇤ 1⇤ 5⇤ 10⇤ 30⇤ 1o 2o 5o 10o20o45o
Figure
At small1:r:that
simulations DM includeand
tryprofiles
(r) to1/r the the corresponding
effects of the existence parameters
104 to
of baryons be plugged
have Moore in the functional forms
of modified
nd eq. (1). profiles
The dashed lines
that are represent
steeper in the the smoothed
center functions
with respect to theadopted
3
DM- for some of the computations
s in
[42]. Most recently, [43]that
has we found such a trend2 re-simulating 10 NFW
Sec. 4.1.3. Notice here provide (3) decimal the
⇥DM GeV⇤cm3 ⇥ haloes digits for the value of r (⇥ ):
significant s s
6 profiles:
eper Einasto profiles (smaller ) are obtained when baryons are
this precision is sufficient for most computations, but more
this possibility we include a modified Einasto profile (that we denote as
added.
102 would be Einasto EinastoB
needed for specific cases, such
nasshort
to precisely reproducewiththe factors (discussed
an J parameter of 0.11. Allinprofiles
Sec.5) for small angular regions around the
etry cuspy: NFW, Moore
Galactic
2
in the following)
and rCenter.
is the coordinate centered in the Galactic Center.
10 assume
Iso
1
mild: Einasto
betterNext,
approximated
we needas triaxial ellipsoids instead
to determine the(e.g. [44]). For thercase
parameters
⇥
ulations show that in general halos can deviate from this simplest form, and the isodensity
10oftypical
1 the Milky
Burkert
s (a scale radius) and s (a typical
smooth: isothermal, Burkert
s fair to say that at the moment we do not have good observational determinations of its
scalealready
efforts density)
madethat enter
studying in each
the stellar tidal of theseseeforms.
streams, Instead
[45]. Thus the
10
of taking
assumption
2 them from the r
individual
simulations, we fix them by imposing that the resulting 10 3profiles
10 2 satisfy
10 1 the findings of
EinastoB = steepened Einasto
astrophysical observations of the Milky Way. Namely, we require:
1 10 102
(effect
5 of baryons?) r kpc⇥You can also read
