IDM2012 Snowden-Ifft Talk2kicp-workshops.uchicago.edu/...snowden-ifft-daniel.pdf ·...
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The Advantages and Challenges of Direc5onal Dark Ma8er Detec5on Dan SnowdenI= Occidental College IDM2012 July 25, 2012
Transcript of IDM2012 Snowden-Ifft Talk2kicp-workshops.uchicago.edu/...snowden-ifft-daniel.pdf ·...
The Advantages and Challenges of Direc5onal Dark Ma8er Detec5on
Dan Snowden-‐I= Occidental College
IDM2012 July 25, 2012
The standard model of direc5onal dark ma8er detec5on
• We live in a dark ma8er halo whose size is supported by thermal, random mo5on, vo = 230 km/s
• And a spiral galaxy whose size is supported by rota5onal mo5on, vrota5on = 220 km/s
• Our rota5onal mo5on through the non-‐rota5ng halo produces a large asymmetry in WIMP veloci5es on the Earth
• We follow the constella5on Cygnus around our galac5c orbit so there is a WIMP-‐wind coming at us from Cygnus
A sidereal modula5on
N
S
45o
z x x z
WIMP “wind” from Cygnus
• Assume, to start, that Cygnus is at a declina5on of 45o and a detector is at a la5tude of 45o
• Recoils will, on average, point down at one 5me and south at another
• The period of this oscilla5on is NOT 24 hours
• The period of rota5on is with respect to Cygnus (sidereal) not our sun (diurnal)
• The oscilla5on, being associated “with the stars” rapidly goes out of phase with terrestrial oscilla5ons, i.e. annual modula5on
Simula5on
Calcula5ons • Calcula5ons support a huge direc5onal asymmetry compared to annual modula5on asymmetry
• Generally speaking the direc5onal signature needs 1000x less events for detec5on than annual modula5on signature, 10s rather than 10s of thousands
• There is an extensive literature on the direc5onal signature
• Lewin and Smith 1996 review
• Gondolo 2002 -‐ 2012
• Morgan and Green 2005 -‐ 2008
Background rejec5on in direc5onal detectors Dark ma8er recoils have a range ~10 smaller than Compton recoil electrons
for the same ioniza5on therefore
to the extent that direc5onal detectors measure the range of events they are fantas5c at background rejec5on.
Advantages summarized • Strong signature requiring 10s of events instead of 10s of thousands of events.
• Not confused by terrestrial modula5ons i.e. explicitly extra-‐terrestrial.
• Implicitly good background rejec5on though zero background not required for detec5on.
• Other uses
• WIMP astronomy
• Stream detec5on
• iDM
• KK Axions
• Neutron source detec5on
Physics Challenge – Straggling
20 keV F -‐-‐-‐-‐-‐-‐-‐-‐-‐-‐-‐-‐-‐>
Physics Challenge – Straggling
50 keV F -‐-‐-‐-‐-‐-‐-‐-‐-‐-‐-‐-‐-‐>
Physics Challenge – Straggling
100 keV F -‐-‐-‐-‐-‐-‐-‐-‐-‐-‐-‐-‐-‐>
Technical Challenge #1 – Range and Volume • The range of a typical 1 keV/amu recoil in a typical solid is about 500 Angstroms. In a typical gas at 1/20 atm it is about 1 mm.
• To set reasonable spin-‐dependent WIMP-‐proton limits one must analyze 50 cm3-‐year of a typical solid or 1 m3 -‐ year of a typical gas at 1/20 atm.
• Neither one of these requirements are daun5ng but the requirement that both be met simultaneously is.
• In either case the size of the recoil is x1000 smaller than the typical size of the volume.
• “Needle in a haystack”
Technical Challenge #2 – Diffusion in TPCs
TPCs can monitor large volumes with very fine grained detectors BUT the charge must be transported over large
distances.
σ =2kTLeE
= 0.5mm T300K
1000V / cmE
L50cm
Technical Challenge #2 – Diffusion in TPCs 0 mm long track in DRIFT 5 mm long track in DRIFT
Technical Challenge #2 – Diffusion in TPCs 0 mm long track in DRIFT 2 mm long track in DRIFT
Technical Challenge #2 – Diffusion in TPCs 0 mm long track in DRIFT 1 mm long track in DRIFT
Technical Challenge #2 – Diffusion in TPCs
• Diffusion places a limit on a detector’s ability to measure range.
• => Direc5onal energy threshold = Limit semng threshold? • Beware diffusion!
Technical Challenge #3 – The head-‐tail detec5on
• Terminology
• What dis5nguishes the head from
the tail? -‐ Hitachi
• Can this be detected with range
straggling and diffusion?
Tail
Head
-‐
-‐
-‐
-‐
-‐
-‐
-‐-‐-‐
DRIFT – Direc5onal Recoil Iden5fica5on From Tracks Started = 1998, US/UK Underground in Boulby, England in 2001 Current opera5ng detector = DRIFT-‐IId Technology = Nega5ve ion TPC with MWPC wire readout
xyz resolu5on = 2 mm, ~<2mm, 0.2 mm, no absolute
Target = 30 Torr CS2 + 10 Torr CF4 Fiducial volume = 800 liters F mass = 33.3 g Limit semng threshold = 50 keVr Talk by Dinesh Loomba this conference
NEWAGE – NEW genera5on WIMP-‐search with Advanced Gaseous tracking device Experiment Started = 2002, Japan Underground in Kamioka, Japan in 2007 Current opera5ng detector = NEWAGE-‐0.3a
Technology = TPC with GEM + µPIC readout
xyz resolu5on = 0.4 mm each & absolute in xy
Target = 152 Torr CF4 Fiducial volume = 15.5 liters F mass = 9.79 g Limit semng threshold = 140 keVr (100 keVr demonstrated)
Talk by Kentaro Miuchi this conference
MIMAC– MIcro-‐tpc MAtrix of Chambers Started = 2005, France Underground in Modane, France in June 2012
Current opera5ng detector = MIMAC prototype Bi-‐Chamber
Technology = TPC with micromegas + pixel readout
xyz resolu5on = 0.35 mm each & absolute in xy
Target = CF4 + 30% CHF3 @ 37.5 Torr Fiducial volume = 5 liters F mass = 1.0 g Limit semng threshold = 20 keVr Talk by Daniel Santos this conference
DM-‐TPC – Dark Ma8er TPC Started = 2007, US Underground in WIPP, USA in 2011 Current opera5ng detector = DMTPC 10 liter
Technology = TPC with micromegas + light and charge readout
xyz resolu5on = 0.256 mm & absolute in xy, Δz coming
Target = CF4 @ 75 Torr Fiducial volume = 9.18 liters F mass = 2.85 g Limit semng threshold = 80 keVr Talk by Shawn Henderson this conference
RHUL Jocelyn Monroe February 24, 2012
Charge
pixel X
pix
el Y
CCD
Chargereadout
Light readout
Light readout
-V
-V
0V+V
F e-
TPC Readout
time (s)
Voltag
e
goal: charge and light= 2->3D
D3 – Direc5onal Dark Ma8er Detector Started = 2008, US Current opera5ng detector = D3 micro prototype
Technology = TPC with GEMs + ATLAS FE-‐I3 pixel chip and ATLAS pixel readout electronics.
xyz resolu5on = 0.05 mm, 0.4 mm, ~0.15 mm & absolute in xy
Target = CF4 ? CS2 ? Fiducial volume = 3 liters F mass = NA Limit semng threshold = NA No talk this conference
Nuclear Emulsion Started = 2010, Japan Underground in LNGS, Italy Current opera5ng detector = Prototype
Technology = Fine grained nuclear emulsion + expansion + microscope readout
Spa5al resolu5on = 100 nm
Target = C(NO),Br,Ag Thresholds = C -‐ 40 keV, Br -‐ 170 keV, Ag -‐ 200 keV in principle
Interac5on = Target is SI, but Br and Ag have spin.
Detector mass of prototype -‐ we will make several g detector
Talk by Tatsuhiro Naka at this conference
Direc5onal Progress – Compton rejec5on
• DRIFT – <3 x 10-‐6 rejec5on
• NEWAGE – <1 x 10-‐6 rejec5on
• DMTPC – <5.6 x 10-‐6 rejec5on NEWAGE Results
Direc5onal Progress – Radon Progeny Recoil (RPR) Background
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222Rn
α
218Po+ 218Po
218Po
α
20 µm
Range = 14 µm
214Pb+
- - - - - -
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-
- 214Pb+
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Holy grail = Fiducializa5on in z
Direc5onal Progress -‐ Direc5onality
0 50 100 150 200 250 300
−10
010
2030
S Recoil Energy (keV)
Opt
imal
and
Ant
i−O
ptim
al D
iffer
ence
s (%
)
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DMTPC Head-‐Tail Results NEWAGE Head-‐Tail Results
DRIFT Head-‐Tail Results DRIFT Range Results
Direc5onal Progress -‐ Limits
Direc5onal Dark Ma8er Community -‐ Direc5onal Conference Series • Cygnus 2007 – Boulby England
• Cygnus 2009 – Boston USA
• Cygnus 2011 – Aussois France
• Cygnus 2013 – Toyama Japan
Backup Slides
Facility Expansion Plans...
14 m x 14 m x 14 m direc5onal dark ma8er detector
