Docstoc

ArDM

Document Sample
ArDM Powered By Docstoc
					               Cracow Epiphany Conference 2010




The Argon Dark Matter
     Experiment

     Małgorzata Harańczyk
         IFJ PAN Kraków

       Sławomir Mania
       University of Silesia
                     Collaboration
Switzerland
ETH Zurich
Zurich University

Spain
University of Granada
CIEMAT

Poland
Soltan Institute for Nuclear Studies, Warszawa
H. Niewodniczański Institute of Nuclear Physics , Kraków
University of Silesia

England
University of Sheffield
                          Małgorzata Harańczyk IFJ PAN Kraków   2
                    Outline

• Conceptual design of the ArDM detector
• Small R&D test setup with LEM readout
• Status of the experiment




                Małgorzata Harańczyk IFJ PAN Kraków   3
                           ArDM

• New generation WIMP detector (simultaneous
  measurement of light and charge)


• 850 kg liquid Argon detector

• Measurement of WIMP recoil energy spectrum
  Energy threshold ~30 keV, 3-D imaging,
  Trigger rate below 1 kHz
                    Małgorzata Harańczyk IFJ PAN Kraków   4
Conceptual design

           A WIMP collides
           with Argon inside
           the detector…

           …transmitting its kinetic
           energy to the nucleus…

           …the Argon nucleus
           recoils….

           Scintillation light and ionization
           electrons are produced from
           interactions with neighbouring       light + charge
           Argon atoms                              signals




    Małgorzata Harańczyk IFJ PAN Kraków                    5
Conceptual design
             • Large volume high electric field,
             Extraction of the ionization electrons
             from the liquid into the gas phase

             • Large area position sensitive charge
             readout with LEM’s (3rd-dimension from
             drift time)

             • Large area VUV sensitive light readout
             with good time resolution (also used for
             trigger)


             Efficient liquid argon purification system

             Careful choice of detector materials (to
             keep low the background due to natural
             radioactivity)
    Małgorzata Harańczyk IFJ PAN Kraków                   6
Conceptual design
                                          80 cm




                                                  120cm




    Małgorzata Harańczyk IFJ PAN Kraków           7
First test – May 2009
 •   22Na   and 137Cs sources

 • Only half (7) of the PMTs were installed

 • No drift electric field


                                    -Light yield is consistent with
                                    expectations (0.5 p.e./keV with 7 PMTs);

                                    -First successful detection of 50 keV
                                    signal in 1t detector;




             Małgorzata Harańczyk IFJ PAN Kraków                            8
Small setup for charge readout R&D
                          Small double-phase argon TPC

                          Max drift length 20 cm (0.5 kV/cm)

                          One LEM 1 mm x 10 cm x10 cm




                         Large Electron Multiplier


           Małgorzata Harańczyk IFJ PAN Kraków                 9
             Small R&D setup




Before …                                                and after measurements .
 A few days long run of stable work with 34 kV/cm in LEM holes

                  Małgorzata Harańczyk IFJ PAN Kraków                              10
                           3D event imaging

                                                                                   Typical cosmic muon
                                                                                           event




                                                             the charge readout with striped LEM and
                                                                        anode plates (2D)
                                                                                    +
                                                                 the light signal to define t0 drift time
                                                                                    =
                                                              a precise 3D reconstruction of the event

Data were taken by MH and SM
during tests at CERN in summer 2009
                                      Małgorzata Harańczyk IFJ PAN Kraków                              11
3D event imaging




   Małgorzata Harańczyk IFJ PAN Kraków   12
                The near future
• Next test of the ArDM detector foreseen in
  February 2010
  14 PMT, drift electric field to measure ionization
• Tests of new types of LEMs are going on with a
  small test setup
  (the full size prototype is still in a design phase)
• Detector ready for underground operation by
  the end of 2010

                     Małgorzata Harańczyk IFJ PAN Kraków   13
                                              SUN LAB
                                              The Sieroszowice Underground LABoratory
                                              -one of three possible locations for
                                              the underground ArDM operation

                                              KGHM copper mine
                                              in the west-southern Poland




Salt cavern
1 km below the surface
2200 m.w.e
very low level of natural
radioactivity background !



                             Małgorzata Harańczyk IFJ PAN Kraków                   14
                    Acknowledgements
 We want to express our gratitude to Andre Rubbia, and Alberto
Marchionni for making it possible to work with ArDM team in CERN.
    We would like to thank Filippo Resnati, and Devis Lussi for
               the kind hospitality extended to us.



                     Małgorzata Harańczyk IFJ PAN Kraków            15
Małgorzata Harańczyk IFJ PAN Kraków   16
                    Background rejection
 Neutrons:                                         Electrons/Gammas:
from radioactive elements in materials             from radioactive elements
and from cosmic muons

⇒ Neutron events look like WIMP-events             ⇒ in Liquid argon e/g events look different
                                                     from WIMP-events

                                                           – Different shape of the scintillation light
                                                           (ratio fast/slow components)


                                                           – Different light/charge ratios




                                 Małgorzata Harańczyk IFJ PAN Kraków                                 17
Małgorzata Harańczyk IFJ PAN Kraków   18
Małgorzata Harańczyk IFJ PAN Kraków   19

				
DOCUMENT INFO
Shared By:
Categories:
Tags:
Stats:
views:0
posted:5/17/2013
language:English
pages:19