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NEWS: Nuclear Emulsion Wimp Search Natalia Di Marco Laboratori Nazionali del Gran Sasso - INFN.

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Presentation on theme: "NEWS: Nuclear Emulsion Wimp Search Natalia Di Marco Laboratori Nazionali del Gran Sasso - INFN."— Presentation transcript:

1 NEWS: Nuclear Emulsion Wimp Search Natalia Di Marco Laboratori Nazionali del Gran Sasso - INFN

2 Outline Directional Dark Matter Searches The NEWS idea: a novel approach to directional detection of DM High Resolution Nuclear Emulsions: NIT Detection Principle NEWS R&D actvity Design sensitivity 2 Moriond Cosmology - March 2014 N. Di Marco

3 Earth revolution gives seasonal modulation Due to solar system movement in the galaxy, the WIMP Flux is expected to be not A directional measurement would provide a strong signature and an unambiguous proof of the galactic origin of DM 3 WIMP wind Sun 230km/s Earth Recoil Nuclei direction Scattered Wimp WIMP cross-section with nuclei A 2 Moriond Cosmology - March 2014 N. Di Marco Directional Dark Matter Searches

4 Current approach: low pressure gaseous detector Targets: CF4, CF4+CS2, CF4 + CHF3 Recoil track length O(mm) Small achievable detector mass due to the low gas density Sensitivity limited to spin-dependent interaction 4 UK USA France Japan Moriond Cosmology - March 2014 N. Di Marco

5 Directional Dark Matter Searches Use solid target: Large detector mass Smaller recoil track lenght O(100 nm) very high resolution tracking detector 5 Moriond Cosmology - March 2014 N. Di Marco

6 Directional Dark Matter Searches Moriond Cosmology - March 2014 N. Di Marco 5 Use solid target: Large detector mass Smaller recoil track lenght O(100 nm) very high resolution tracking detector Nuclear Emulsion based detector acting both as target and tracking device

7 Directional Dark Matter Searches Moriond Cosmology - March 2014 N. Di Marco 5 Use solid target: Large detector mass Smaller recoil track lenght O(100 nm) very high resolution tracking detector Nuclear Emulsion based detector acting both as target and tracking device NEWS: Nuclear Emulsion WIMP search Italy Napoli Univeristy Federico II LNGS – INFN Bari University Japan Nagoya University

8 Nuclear Emulsion 6 AgBr AgBr crystal size m After the passage of charged particles through the emulsion, a latent image is produced. The emulsion chemical development makes Ag grains visible with an optical microscope A long history, from the discovery of the Pion (1947) to the evidence of oscillation in appearance mode (OPERA, 2014) Moriond Cosmology - March 2014 N. Di Marco

9 Nuclear Emulsion 7 Lighter nuclei (longer range at same recoil energy) Sensitivity to low WIMP mass Ag Br O N C A% Weight I Ag Br S O N C H Chemical composition of nuclear emulsions Moriond Cosmology - March 2014 N. Di Marco

10 Nuclear Emulsion 8 Range [nm] Recoil energy [keV] Br range < 300 nm WIMP velocity < 800 km/sec Take e.g. M WIMP ~ 150 GeV/c 2 Recoil energy < 500 keV Max recoil energy [keV] WIMP mass [GeV/c 2 ] Br Ag OPERA emulsion films: Silver grain size ̴ 200 nm too large to record nanometric nuclear recoils Moriond Cosmology - March 2014 N. Di Marco

11 NIT emulsion films: Nano Imaging Trackers 9 70 nm crystal100 nm crystal200 nm crystal 35 nm crystal Range distribution [nm] Recent developments Natsume et al, NIM A575 (2007) 439 Moriond Cosmology - March 2014 N. Di Marco

12 Concept of readout: step 0 10 Expansion of emulsion film Chemical treatment Moriond Cosmology - March 2014 N. Di Marco Film expansion technique (T. Naka et al., NIMA581 (2007) 761)

13 Concept of readout: step 0 Signal track Random noise Film expansion technique (T. Naka et al., NIMA581 (2007) 761) Elliptical shape Circular shape 10 Expansion of emulsion film Chemical treatment Moriond Cosmology - March 2014 N. Di Marco

14 11 Moriond Cosmology - March 2014 N. Di Marco Concept of readout: step I Scanning with optical microscope and shape recognition analysis Automatic selection of candidate signals by optical microscopy. Full area scan. Resolution 200 nm (one order of magnitude better than the OPERA scanning system), scanning speed 20 cm 2 /h

15 12 Test using 400 keV Kr ions Moriond Cosmology - March 2014 N. Di Marco Concept of readout: step I Scanning with optical microscope and shape recognition analysis

16 12 Direction detected! θ Test using 400 keV Kr ions Moriond Cosmology - March 2014 N. Di Marco Concept of readout: step I Scanning with optical microscope and shape recognition analysis Nucl.Instrum.Meth. A680 (2012) 12-17

17 13 N. Di Marco Concept of readout: step II Scanning with X-ray microscope of preselected zones Pin-point check at X-ray microscope of candidate signals selected by optical readout. Resolution ̴ 30 nm Moriond Cosmology - March 2014

18 14 330nm 236nm 486nm 600nm Optical microscope X-ray microscope N. Di Marco Concept of readout: step II Scanning with X-ray microscope of preselected zones Moriond Cosmology - March 2014

19 14 330nm 236nm 486nm 600nm Optical microscope X-ray microscope Matching of recoiled tracks between Optical and X-ray microscope Success rate of matching 572/579=99% N. Di Marco Concept of readout: step II Scanning with X-ray microscope of preselected zones Moriond Cosmology - March 2014

20 14 330nm 236nm 486nm 600nm Optical microscope X-ray microscope Matching of recoiled tracks between Optical and X-ray microscope Success rate of matching 572/579=99% N. Di Marco Concept of readout: step II Scanning with X-ray microscope of preselected zones angular resolution [degrees] optical microscope range: nm X-ray microscope range: nm Moriond Cosmology - March 2014

21 R&D activity NIT technology Optical and X-ray read-out system Intrinsic background measurement Angular resolution measurement, neutron test beam Full MC simulation 15 Moriond Cosmology - March 2014 N. Di Marco

22 R&D activity NIT technology Optical and X-ray read-out system Intrinsic background measurement Angular resolution measurement, neutron test beam Full MC simulation 15 Moriond Cosmology - March 2014 N. Di Marco

23 Sensitivity Zero-background hypothesis 90% C.L. 100 nm tracking threshold directionality information not included 16 Moriond Cosmology - March 2014 N. Di Marco

24 Conclusions A novel approach for directional Dark Matter searches is proposed in NEWS Novel nuclear emulsion technique with nanometric spatial resolution The use of a solid target would allow to explore the low cross section sector in the phase space indicated by recent direct search experiments but using a complementary an powerful approach NIT (Nano Imaging Tracker) Read-out system based both on optical (200 nm resolution) and X-ray microscopy (30 nm resolution) … from the R&D to the experiment in few years Moriond Cosmology - March 2014 N. Di Marco 17


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