The SENSEI † project how to look for DM-electron scattering events Javier Tiffenberg Fermi National Laboratory March 25, 2017 † S ub- E lectron- N oise S kipperCCD E xperimental I nstrument 1 Cosmic Visions Workshop March 23, 2017
Motivation for SENSEI: a detector that can do this NOW Heavy Dark Photon Light Dark Photon �� - �� �� - �� � � � � � �� - �� � � � �� - �� � ������� � � �������� � � � � �� - �� ��� �� � ��� �� - �� �� - �� ��� �� �� ��� �������� ������� �� - �� �� - �� ��� � - ������ σ � [ �� � ] σ � [ �� � ] �� - �� ��� �� � ��� �� - �� �� - �� ������ - �� �� - �� �� - �� ������ �� - �� ������ �� - �� � - � � � � � ��� � - �� �� - �� ������ �� - �� �� - �� ������� � �� = � / � � � �� = � �� - �� �� - �� � �� �� � �� � �� � �� � � �� �� � �� � � χ [ ��� ] � χ [ ��� ] Plots from: Rouven Essig, Tomer Volansky & Tien-Tien Yu. 2 Cosmic Visions Workshop March 23, 2017
How? use CCDs as target to record the ionization produced by DM CCD pixel conduction band hole DM electron valence band Si + 3 Cosmic Visions Workshop March 23, 2017
CCD: readout P 1 P 2 P 3 P 1 P 2 P 3 3x3 pixels CCD state 1 H 3 H 2 channel H 1 2 horizontal register stop H 3 H 2 channel H 1 stop 3 H 3 H 2 .. .. .. H 1 sens node P 1 P 2 P 3 P 1 P 2 P 3 P 1 P 2 P 3 7 ampli fi er capacitance of the system is set by the SN: C=0 . 05pF → 3 µ V/e 4 Cosmic Visions Workshop March 23, 2017
CCD: readout sens H H SW OG VR V node Accumulate the charge in the SW and reset the SN voltage 5 Cosmic Visions Workshop March 23, 2017
CCD: readout sens H H SW OG VR V node Disconnect the SN so it’s floating. Measure the baseline voltage in the SN. 5 Cosmic Visions Workshop March 23, 2017
CCD: readout sens H H SW OG VR V node Move the change to the SN and measure the shift in the voltage 5 Cosmic Visions Workshop March 23, 2017
CCD: readout 6 Cosmic Visions Workshop March 23, 2017
CCD: readout excellent for removing high frequency noise but sensitive to low frequencies 6 Cosmic Visions Workshop March 23, 2017
Readout noise: empty pixels distribution 4 10 σ = 1.8 e 3 10 2 10 10 1 -30 -20 -10 0 10 20 30 pixel value /e 2 e − readout noise roughly corresponds to 50 eV energy threshold 7 Cosmic Visions Workshop March 23, 2017
Lowering the noise: Skipper CCD H 3 H 2 H 1 horizontal register channel stops H 3 H 2 H 1 H 3 H 2 H 1 P 3 P 2 P 1 P 3 P 2 P 1 P 3 P 2 P 1 ampli fi er readout stage is replaced 8 Cosmic Visions Workshop March 23, 2017
Lowering the noise: Skipper CCD Main difference: the Skipper CCD allows multiple sampling of the same pixel without corrupting the charge packet. The final pixel value is the average of the samples Pixel value = 1 N Σ N i (pixel sample) i Idea proposed in 1990 by Janesick et al. (doi:10.1117/12.19452) 9 Cosmic Visions Workshop March 23, 2017
Lowering the noise: Skipper CCD Main difference: the Skipper CCD allows multiple sampling of the same pixel without corrupting the charge packet. The final pixel value is the average of the samples Pixel value = 1 N Σ N i (pixel sample) i Idea proposed in 1990 by Janesick et al. (doi:10.1117/12.19452) Regular CCD Skipper CCD signal pixel charge pedestal measurement high frequency noise low frequency noise 9 Cosmic Visions Workshop March 23, 2017
SENSEI: Sub-Electron-Noise SkipperCCD Experimental Instrument Awarded proposal: Fermilab LDRD 2016 - PI Javier Tiffenberg Develop a CCD-based detector with an energy threshold close to the silicon band gap (1.1 eV) and a readout noise of 0.1 electrons using a new generation skipper CCD developed by the LBNL MicroSystems Lab Plan Build the first working detector using Skipper-CCDs. Optimize the operation parameters and running conditions. Produce a low radiation package for the Skipper-CCDs. Install the detector in a low radiation environment (MINOS). Validate the technology for DM and ν experiments. 10 Cosmic Visions Workshop March 23, 2017
SENSEI: First working instrument using SkipperCCD tech Sensors Skipper-CCD prototype designed by LBL MSL 200 & 250 µ m thick, 15 µ m pixel size Two form factors 4k × 1k (0.5gr) & 1.2k × 0.7k pixels Parasitic run, optic coating and Si resistivity ∼ 10kΩ 4 amplifiers per CCD, three different RO stage designs Instrument System integration done at Fermilab Custom cold electronics Modified DES electronics for read out Firmware and image processing software Optimization of operation parameters 11 Cosmic Visions Workshop March 23, 2017
Image taken with SENSEI: 4000 samples per pixel (processed) m] 250 µ y [pix=15 2000 240 1500 230 220 1000 210 500 200 0 50 60 70 80 90 100 110 120 x [pix=15 m] µ 12 Cosmic Visions Workshop March 23, 2017
Image taken with SENSEI: 4000 samples per pixel (processed) m] 250 µ y [pix=15 2000 240 1500 230 X-ray 220 1000 210 500 200 0 50 60 70 80 90 100 110 120 x [pix=15 m] µ 12 Cosmic Visions Workshop March 23, 2017
Image taken with SENSEI: 4000 samples per pixel (processed) m] 250 µ y [pix=15 2000 240 muon 1500 230 X-ray 220 1000 210 500 200 0 50 60 70 80 90 100 110 120 x [pix=15 m] µ 12 Cosmic Visions Workshop March 23, 2017
Image taken with SENSEI: 4000 samples per pixel (processed) m] 250 µ y [pix=15 2000 240 muon 1500 230 X-ray 220 1000 210 500 "empty pixels" 200 0 50 60 70 80 90 100 110 120 x [pix=15 m] µ 12 Cosmic Visions Workshop March 23, 2017
Charge in pixel distribution. Counting electrons: 0, 1, 2.. 13 Cosmic Visions Workshop March 23, 2017
Charge in pixel distribution. Counting electrons: 0, 1, 2.. 13 Cosmic Visions Workshop March 23, 2017
Counting electrons: ..38, 39, 40.. 14 Cosmic Visions Workshop March 23, 2017
Counting electrons: ..38, 39, 40.. 14 Cosmic Visions Workshop March 23, 2017
√ Noise vs. #samples - 1/ N 15 Cosmic Visions Workshop March 23, 2017
Whats next: Installation @MINOS & low radiation package Technology demonstration: installation at shallow underground site NOvA NuMI building SENSEI 107 m MINOS Hall 16 Cosmic Visions Workshop March 23, 2017
Whats next: Installation @MINOS & low radiation package RO electronics optimization & integration characterization MINOS installation MINOS run start Jun16 Jan16 Jan17 Apr17 Dec17 TSW approved Clean-room permission to start operations Low radiation package Commissioning of 1gr at MINOS by the end of April 2017 17 Cosmic Visions Workshop March 23, 2017
SENSEI: DM search operation mode Counting electrons ⇒ noise has zero impact It can take about 1h to readout a 4kx4k sensor Dark Current is the limiting factor It’s better to readout continuously to minimize the impact of the DC Number of DC events (100 g y) DC = 1 × 10 − 3 e pix − 1 day − 1 DC = 10 − 5 e pix − 1 day − 1 Thr /e 1 × 10 8 7 × 10 5 1 2 × 10 4 2 0.2 3 × 10 − 2 3 × 10 − 8 3 Measured upper limit for the DC in CCDs is: 1 × 10 − 3 e pix − 1 day − 1 arXiv:1611.03066 Could be orders of magnitude lower. Theoretical prediction is O ( 10 − 7 ) 18 Cosmic Visions Workshop March 23, 2017
SENSEI: reach of a 100g, zeroish-background experiment Light Dark Photon �� - �� �� - �� �������� �� - �� � � � � � � � � �� - �� � � � � � ������� � � � � �� - �� � � σ � [ �� � ] � �� - �� � � � � � � � � �� - �� ������ - �� �� - �� �� - �� ������ � � �� - �� - � � � � �� - �� � �� = � / � � �� - �� � �� �� � �� � �� � �� � � χ [ ��� ] Rouven Essig, Tomer Volansky & Tien-Tien Yu. 19 Cosmic Visions Workshop March 23, 2017
SENSEI: reach of a 100g, zeroish-background experiment Heavy Dark Photon All Experiments ( Kinetic Mixing + Elastically Coupled DM ) LHC 10 - 4 10 - 5 LEP 10 - 6 DarkLight E787 / 949 @ BNL BaBar @ JLab 10 - 7 m χ / m A' ) 4 PADME @ LNF MiniBooNE 10 - 8 FNAL VEPP - 3 @ 10 - 9 @ BINP MMAPS @ Cornell 2 α D ( 10 - 10 JLab Belle II E137 BDX @ 10 - 11 y = ϵ NA64 @ CERN Scalar Relic Target 10 - 12 LSND 10 - 13 Fermion Relic Target SLAC DARK-SECTORS 10 - 14 LDMX @ arXiv:1608.08632 10 - 15 10 - 16 1 10 10 2 10 3 m χ ( MeV ) 20 Cosmic Visions Workshop March 23, 2017
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