NEWSdm experiment Directional Dark Matter Search with Super-high - PowerPoint PPT Presentation

NEWSdm experiment Directional Dark Matter Search with Super-high resolution Nuclear Emulsion Tatsuhiro NAKA KMI, Nagoya University on behalf of NEWSdm collaboration 1

Direction sensitive dark matter detector with solid Direction sensitive dark matter with solid detector  Super-high resolution device using Our device case Density 3.2 g/cm3 capability of detecting nano-scale tracks Main Target : CNO + AgBr  Readout technologies for such very 100 GeV/c 2 short length tracks 50 GeV/c 2 20 GeV/c 2  Understanding and rejection of 10 GeV/c 2 backgrounds 2

Direction sensitive dark matter with solid detector New Idea amd on studying This talk  Diamond Microscope imaging of luminescence due to N-V center in diamond Phys. Rev. D. 96 035009 (2017) Super-fine grained Nuclear emulsion  Anisotorpic crystal (e.g., ZnWO4) (Nano Imaging Tracker : NIT)  Carbon nano tube First detector demonstrated capability of tracking Carbon nanotube target + gaseous TPC to low-velocity nuclear recoil arXiv:1412.8213 [physics.ins-det]  Rock (but not directional search) Crystal defect tracking in Ancient mineral → already M or G year exposure arXiv:1811.06844v1 [astro-ph.CO] 16 Nov 2018 3

NEWSdm exp xperim iment [N [Nuclear Emuls lsion for WIM IMPs Search – dir irectional l measurement] Chiba METU Ankara Nagoya Gyeongsang LPI RAS Moscow Bari http://news-dm.lngs.infn.it JINR Dubna GSSI LOI under review by the LNGS science committee SINP MSU Moscow LNGS INR Moscow Napoli Yandex School of Data Analysis Roma https://arxiv.org/abs/1604.04199 4

Concept of NEWSdm experiment Device self-production Super-high resolution device Surface laboratory exposure using telescope Chemical development treatment Underground laboratory Readout + analysis Using microscope techniques 5

Nuclear Emulsion Device Polymer (C, (N,O)) Charged Particle Silver halide crystal (AgBr) * ~ 200 nm  Kind of photographic film  High spatial resolution  4π tracking Latent image specks Development treatment Silver grains Standard nuclear emulsion 100 µm Very fine crystal controlled about 10 Crystal size : 200 nm nm to detect 100 nm scale tracks Detectable track length : > O(1) µm 6

Self-production of Nano Imaging Tracker(NIT) Controlled AgBr crystal Usual type Super-resolution standard 500nm 500nm 500nm 500nm Current standard Device : UNIT Nano Imaging Tracker [NIT] @ Nagoya Univ. NIT crystal size : 44 nm NIT-60 ・ Production time : 4-5 hours /batch Finest grain emulsion : ・ One butch : ~ 100 g (+ 300 g) Ultra-NIT [UNIT] crystal size : 25 nm (there are 2 type machines) ⇒ kg scale production is possible using this machine. T. Naka et al., Nucl. Inst. Meth. A 718 (2013) 519-521 7 T. Asada, T. Naka + , Prog Theor Exp Phys (2017) 2017 (6): 063H01

Properties of NIT device  Intrinsic radioactivity : U-238 Th-232 K-40 Ag-110m C-14 27 6 35 (~400) 24000 [mBq/kg] • K-40 reduction : 69020 (first type) → 35 mBq/kg by KBr → NaBr for AgBr creation and use high deionized gelatin • Ag-110m : not confirmed yet first measured batch : ~ 400 mBq/kg Elemental composition of NIT For low-mass DM For high-mass DM s recent batch : < 150 mBq/kg Mass fraction Atomic Fraction • C-14 : AMS measurement result. Consistent with natural abundance. → if replace to synthetic polymer, it will be reduced more than 10 -3 Ag 0.44 0.10 Br 0.32 0.10  Intrinsic neutron background (SOURCES + Geant4): I 0.019 0.004 C 0.101 0.214 Emission [/kg/y] Rate for > 100 nm tracks [/kg/y] O 0.074 0.118 Intrinsic neutron ~ 1.2 ~ 0.1 N 0.027 0.049 Detail shown in Astropart. Phys. 80 (2016)16-21 H 0.016 0.410 8 S, Na + others ~ 0.001 ~ 0.001

Low-velocity ion tracking Can use ion implantation as calibration source SEM image of low-velocity Carbon ion (100keV) - Mono energy ( ± 0.1 keV) 1 um - Good direction uniformity (<10 mrad) - Now, C from CO 2 ・ Ar, Kr ( various kind ions are also possible) Low velocity ion created by an ion- AgBr crystal has good sensitivity implantation system at Nagoya University about Carbon (100 % consistent sensitivityy) 9 2019/3/8

Readout technologies One more machine will be LNGS Machine for device • Event selection constructed Napoli quality check • Phase contrast imaging Toho U. Nagoya • Event selection • Plasmon analysis x 2 10

Optical microscope system and analysis flow Standard optical microscope LSPR analysis Phase contrast imaging Further new analysis [under studying] scanning [on going] [will be newly installed] [ under studying ] 10^7 events/month 10^5 events/month Current Speed : ~30 g/y ~10^3 events/month  3D super-resolution  Phase contrast  Elliptical event selection  Super-resolution : ~10 nm analysis with  Roughly event selection imaging  Spectrum analysis plasmonics with high speed  Contaminated dust  Machine learning  Destructive analysis  On-line event analysis discrimination using oxidation method ~ 100 g/month scale (~ kg/y)  Expansion method Yandex@Russia, Napoli To be constructed soon ~ kg /month scale (~ 10 kg/y) Cutting-edge technologies will be installed T. Katsuragawa et al., JINST 12, T04002(2017)

Sub-micron length track readout capability Calibration by C 60 keV C 60 keV Cleary observed angular Direction sensitive track length distribution threshold in this algorithm 11µm ⇒ angular resolution ~ 30 deg. ⇒ > ~ 190 nm Energy threshold K. Kimu mura ra and T. Naka, Nucl cl. Inst st. Meth. A 680 680 (201 012) 12 12-17 17 > ~ 60 keV (eff. ~ 10 % ⇒ to be improve by upgrade optical condition) T. Katsuragawa et al, JINST 12 T04002 (2017) 12

Demonstration of direction sensitive nuclear recoil detection due to 14.8 MeV neutrons signal region Red : confirmed track by X-ray microscope after optical microscope readout Direction of neutron Mostly detected target was Br recoil [ < 200 keV ] → difference condition from current one Now on studying CNO recoil demonstration due to 565-700 keV (Li-p nuclear fission reaction) 13

Main source Technologies Expected rejection power or event rate Physical BG (> 10 6 or more rejection power Electrons C- 14 β Crystal temperature dependence Environment gamma ( M. Kimura et al., NIM A 845 (2017) 373 ) (< O(1) /kg/day)) *now on Crystal sensitivity control studying Image and plasmonic analysis Synthetic Polymer > 10 3 or more ~ 3 x 10 -4 /kg/day or less Neutron Intrinsic (α, n) - Astropart. Phys. 80 (2016)16-21 Environment Water shield < 1E-4/kg/day Cosmic-ray Recoiled nuclei Coincidence with MIP sensitive emulsion *on studying using simulation (~O(10 -4 )/kg/day * now on Spallation neutron (under studying with simulation) study) Nonphysical BG Contaminated dust (under studying) Clean room Under studying (at least > 10 6 or more, in Phase contrast imaging Plasmonic analysis and image processing principle it should not be Machine learning background ) Chemical treatment 14

Further signal discrimination from backgrounds Plasmonic optical response + machine learning Phase contrast imaging Contaminated background Low-velocity ion (signal) Scatter light spectrum information due to plasmonic effect Signal region Blue: Cion 200keV Red : backgournd New information to distinguish signal from background by phase-contrast imaging Such new analysis studies are now on going 15

Super-resolution microscopy using LSPR information toward lower-threshold tracking C 30 keV Polarization light dependence Electron microscope image Calibration by C 30 keV 190 nm (shape analysis) → 120 nm Shift of barycenter is important information 16 for nano-scale structure

Dark matter sensitivity 10 kg∙year simulated sensitivity [90 % C.L.] + zero BG Demonstrated new tech. Case for current readout ability Current Case for extrapolation lower energy Case for intrinsic detection ability Intrinsic Depends on readout technologies Our device case Density 3.2 g/cm3 Main Target : CNO + AgBr Current readout performance 100 GeV/c 2 Lower-energy readout 50 GeV/c 2 Device potential 20 GeV/c 2 10 GeV/c 2 NIT detector / CNO sensitive / no Bkg no directionality Simulation limit is “energy > 5 keV for all atoms (SRIM limit)” & “Sensitivity > 0.1 % (Simulation statistics limit;10 event)” Device potential : 10 keV of C recoil (> ~ 10% eff. and 45 ° angl. Res. 17

Underground laboratory at LNGS Device Production facility New production machine Hall F Motivation of New Underground facility  Device self-production in underground  Device handling in clean room  Chemical development Discussion started from 2017, and construction from beginning of 2018 18

New Underground emulsion facility Feb. 2018 ~ : started construction and commissioning of the production machine at Nagoya ( ⇒ transported to LNGS from Sep. 2018) Feb. 2019 ~ : Started test production first time at underground + clean room and other infrastructure are on constructing Up to April : overall confirmation of underground emulsion facility with clean room α -ray track in first LNGS-emulsion First production in LNGS succeeded !! 19

Equatorial telescope for directional search Future prospect for > 1kg scale detector Future prospect for ~ 10-100 g scale detector Earth axis Polyethylene CYGNUS * Under discussion Source Rate [/10kg/y] Environmental γ -rays (2.0 +- 0.2) x 10 4 Environmental neutrons O(10 -2 ) 20 Cosmogenic neutrons 1.4 +- 0.1