The search for Majorana neutrinos with a background-free gaseous - - PowerPoint PPT Presentation
The search for Majorana neutrinos with a background-free gaseous Xenon TPC at the tonne scale F . Monrabal on behalf The NEXT coll. 1 The Majorana neutrino challenge Lifetime ~10 27 -10 28 years 1 signal event in a tonne of active
F . Monrabal on behalf The NEXT coll.
Lifetime ~1027-1028 years 1 signal event in a tonne
Lifetime ~1030 years 1 signal event in a 100 tonne of active volume per year
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Experiment counts/ (keV·kg·year) counts/(ROI·ton·year) Gerda 1.0x10-3 4 Kamland-Zen 1.18x10-2 40 EXO 1.7x10-3 255 CUORE 1.4x10-2 107 NEXT 4x10-4 10
Nature, 510, 229-234 arXiv:1905.07667v1 JHEP05 (2016) 159
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Prototypes NEW (~10kg) NEXT-100 (100 kg) NEXT (~1000 kg)
See J.M. Benlloch talk!
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Extrapolation of the current NEXT-100 concept Reduced radioactive budget by replacing the PMTs with SiPM. Symmetric TPC Energy and tracking functions remain independent
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EL mesh Design voltage of cathode and HVFT is very close to NEXT-100 SiPM radio-pure substrates already in hand.
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Differences with NEXT-100 Symmetric detector: Two sizes of SiPMs in the same plane, need to develop an integrated electronics. Gas mixtures to reduce diffusion Operation with cold Xenon: We need to reduce SiPM dark current
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We will use a vertical symmetric detector with the cathode in the center. This simplifies the design of the high voltage feedthrough and reduces total drift length. Sensor planes will have two SiPMs sizes. Similar dynamic range Energy function implemented in the opposite size of the amplification (as usual) E E
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Xenon-CH4 mixtures could provide very small electron diffusion At low concentrations (<1%) resolution is maintained Xenon-Helium mixtures have a similar effect on diffusion but for a larger He concentrations. Much smaller effect on light production
2016 JINST 11 C02007
Nucl.Instrum.Meth. A905 (2018) 82-90. JINST 14 (2019) no.08, P08009 arXiv:1906.03984 [physics.ins-det]
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We need to reduce the SiPM dark current Operation at lower temperatures! We still want to operate in the gas phase, and we have a large phase space for that!
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FAT-GEM: Field Assisted Transparent Gas electroluminescenceMultiplier Energy resolution still limited by the number
‘Super-thick’ (5mm) acrylic GEM with semitransparent electrodes
arXiv:1907.03292v1 [physics.ins-det]
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Detecting “tagging” the Ba++ signaling a ββ0ν process has been a long sought holy grail of xenon chambers.
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Noble price in Chemistry 2014: Development of super- resolved fluorescence microscopy
J.Phys.Conf.Ser. 650 (2015) no.1, 012002
Demonstration of Single-Barium-Ion Sensitivity for Neutrinoless Double-Beta Decay Using Single-Molecule Fluorescence Imaging
by D. Nygren
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Biology Physics Wet medium Dry phase Molecules that fluoresce in wet Molecules that fluoresce in dry Small density of molecules Dense target with only 1 active molecule Small surrounding background Large, but measurable background Large numerical apertures thanks to immersion oil techniques Limited numerical aperture
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Biology Physics Wet medium Dry phase Molecules that fluoresce in wet Molecules that fluoresce in dry Small density of molecules Dense target with only 1 active molecule Small surrounding background Large background Large numerical apertures thanks to immersion oil techniques Limited numerical aperture
All that already demonstrated for Ba++ in the proof of concept!
Collaboration)
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Fluorescence Intensity per Pixel (arb)
Single detected ion
Based on aza-crowns.
monocolor molecules: on/off
spectra separation.
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Density functional theory gas phase structures Frontier molecular orbital energy diagram
the torsion of the phenyl group allowing $\pi$-coordination breaks the planarity with the rest of the fluorophore, modifying HOMO and LUMO energy levels
FBI molecule developed at DIPC/EHU by the F . Cossio group
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https://arxiv.org/abs/1909.02782
In order to maximise the efficiency of capturing the Ba2+ ion we should create a dens monolayer of molecules and be able to scan all of it after a candidate event. ~106 molecules/um2 We should be able to find 1 molecule in a sensor of ~10x10mm2 Large background from the non-chelated molecules. Optimal packaging and sensor size is still being studied
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One possibility is to adapt the TIRF technique to the dry phase A different approach is the use of two photon absorption technique that allows for self-focusing
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When focusing our laser to minimise background we need to move our focusing spot to scan the whole sample Interesing possibilities like wide-field microscopy or espacio-temporal focusing allow for sampling larger surfaces on every laser pulse.
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demonstrate/measure ion capture.
capture, collective effects,…
, TPA,…
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years lifetime. Background rates at 1 evt/tonne·year.
level.
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Back-up
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