The SENSEI project how to look for DM-electron scattering events - - PowerPoint PPT Presentation
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
how to look for DM-electron scattering events
Javier Tiffenberg
Fermi National Laboratory
March 25, 2017
† Sub-Electron-Noise SkipperCCD Experimental Instrument
1 Cosmic Visions Workshop March 23, 2017
Motivation for SENSEI: a detector that can do this NOW
Light Dark Photon
σ []
Heavy Dark Photon
σ []
2 Cosmic Visions Workshop March 23, 2017
How? use CCDs as target to record the ionization produced by DM
Si +
DM
hole
conduction band
electron
valence band
3 Cosmic Visions Workshop March 23, 2017
CCD: readout
1 2 3 7
P2 P1 P3 P2 P1 P3
3x3 pixels CCD
P2 P1 P3 P2 P1 P3 P2 P1 P3 H2 H1 H3 H2 H1 H3 H2 H1 H3
amplifier channel stop horizontal register sens node channel stop
state
capacitance of the system is set by the SN: C=0.05pF→ 3µV/e
4 Cosmic Visions Workshop March 23, 2017
CCD: readout
sens node
Accumulate the charge in the SW and reset the SN voltage
5 Cosmic Visions Workshop March 23, 2017
CCD: readout
sens 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 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
pixel value /e
10 20 30 1 10
2
10
3
10
4
10
σ = 1.8 e
2 e− readout noise roughly corresponds to 50 eV energy threshold
7 Cosmic Visions Workshop March 23, 2017
Lowering the noise: Skipper CCD
P2 P1 P3 P2 P1 P3 P2 P1 P3 H2 H1 H3 H2 H1 H3 H2 H1 H3
amplifier channel stops horizontal register
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
NΣN 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
NΣN i (pixel sample)i
Idea proposed in 1990 by Janesick et al. (doi:10.1117/12.19452)
low frequency noise Regular CCD Skipper CCD pedestal signal high frequency noise pixel charge measurement
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 µm thick, 15 µm 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] µ x [pix=15 50 60 70 80 90 100 110 120 m] µ y [pix=15 200 210 220 230 240 250 500 1000 1500 2000
12 Cosmic Visions Workshop March 23, 2017
Image taken with SENSEI: 4000 samples per pixel (processed)
m] µ x [pix=15 50 60 70 80 90 100 110 120 m] µ y [pix=15 200 210 220 230 240 250 500 1000 1500 2000
X-ray
12 Cosmic Visions Workshop March 23, 2017
Image taken with SENSEI: 4000 samples per pixel (processed)
m] µ x [pix=15 50 60 70 80 90 100 110 120 m] µ y [pix=15 200 210 220 230 240 250 500 1000 1500 2000
X-ray muon
12 Cosmic Visions Workshop March 23, 2017
Image taken with SENSEI: 4000 samples per pixel (processed)
m] µ x [pix=15 50 60 70 80 90 100 110 120 m] µ y [pix=15 200 210 220 230 240 250 500 1000 1500 2000
X-ray muon "empty pixels"
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
NuMI building MINOS Hall 107 m
NOvA
16 Cosmic Visions Workshop March 23, 2017
Whats next: Installation @MINOS & low radiation package
Jan16 Jun16 Jan17 Dec17 start MINOS installation RO electronics integration
characterization Apr17 MINOS run
Clean-room Low radiation package
TSW approved
permission to start operations
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) Thr /e DC = 1 × 10−3 e pix−1day−1 DC = 10−5 e pix−1day−1 1 1×108 7×105 2 2×104 0.2 3 3×10−2 3×10−8 Measured upper limit for the DC in CCDs is: 1 × 10−3 e pix−1day−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 []
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
Scalar Relic Target Fermion Relic Target
BaBar LHC LEP BDX@ JLab E787/949@ BNL PADME@ LNF LDMX@ SLAC VEPP- 3 @ BINP NA64 @ CERN MMAPS @ Cornell DarkLight @ JLab
Belle II
MiniBooNE @ FNAL LSND E137
1 10 102 103 10- 16 10- 15 10- 14 10- 13 10- 12 10- 11 10- 10 10- 9 10- 8 10- 7 10- 6 10- 5 10- 4
mχ (MeV) y =ϵ
2αD (
m χ/mA')4
All Experiments (Kinetic Mixing +Elastically Coupled DM)
DARK-SECTORS arXiv:1608.08632
20 Cosmic Visions Workshop March 23, 2017
SENSEI: reach of a 100g, zeroish-background experiment
Heavy Dark Photon: complemetary to LDMX
σ []
21 Cosmic Visions Workshop March 23, 2017
SENSEI: electron recoil background requirements
The sensitivity is dominated by the lowest energy/charge bin
σ []
10-7 10-6 10-5 10-4 10-3 0.01 0.1 1 Noralized rate Mχ = 10 MeV ∝1/q2 FDM 10 Q 9 8 7 6 5 4 3 2 1 11
Rouven Essig, Tomer Volansky & Tien-Tien Yu.
22 Cosmic Visions Workshop March 23, 2017
SENSEI: electron recoil background requirements Back of the envelope calculation
A 100g detector that takes data for one year → Expo = 36.5kg · day Assuming same background as in DAMIC: 5 DRU (events·kg−1·day−1·keV−1) in the 0-1keV range → Nbkg = 36.5 kg · day × 5 DRU = 182.5 events Dominated by external gammas → flat Compton spectrum
23 Cosmic Visions Workshop March 23, 2017
SENSEI: electron recoil background requirements Back of the envelope calculation
A 100g detector that takes data for one year → Expo = 36.5kg · day Assuming same background as in DAMIC: 5 DRU (events·kg−1·day−1·keV−1) in the 0-1keV range → Nbkg = 36.5 kg · day × 5 DRU = 182.5 events Dominated by external gammas → flat Compton spectrum #events [e-]
5 4 3 2 1 278 1keV
182.5 events over the 278 charge bins in the 0-1keV range
Expect 0.65 bkd events in the lowest (2 e−) charge-bin
23 Cosmic Visions Workshop March 23, 2017
SENSEI path Summary
Demonstrated technology: working detector Demonstrated bkg: no R&D needed.
◮ this level already reached by running experiments
Minimal R&D required for the packaging of the sensors. 100 g construction could start on FY18.
◮ 1.2 M$ in 2 yrs (scaled from DAMIC experience)
Complementary to LDMX and DAMIC-1K Small scale demonstration at the MINOS. Results by the end of 2017. MINOS site is good up to a 10g experiment. SURF/Snolab for 100g.
24 Cosmic Visions Workshop March 23, 2017
25 Cosmic Visions Workshop March 23, 2017
SENSEI budget draft
M&S Effort Total
350 k$ 100 k$ 450 k$
200 k$ 0 k$ 200 k$
115 k$ 100 k$ 215 k$
0 k$ 50 k$ 50 k$
150 k$ 50 k$ 200 k$ Total 815 k$ 300 k$ 1.15 M$
26 Cosmic Visions Workshop March 23, 2017
DAMIC background
27 Cosmic Visions Workshop March 23, 2017
SuperCDMS SNOLAB projected background
“Singles”BackgroundRates ElectronRecoil NuclearRecoil(×10
−6)
(counts/kg/keV/year) Ge HV Si HV Ge iZIP Si iZIP Ge iZIP Si iZIP Cohe re nt Ne utrinos 2300. 1600. De te ctor-Bulk Contamination 21. 290. 8.5 260. MaterialActivation 1.0 2.5 1.9 15. Non-Line-of-SightSurfaces 0.00 0.03 0.01 0.07 – Bulk Mate rial Contamination 5.4 14. 12. 88. 440. 660. Cave rn Environme nt – – – – 510. 530. Cosmoge nic Ne utrons 73. 77. T
27. 300. 22. 370. 3300. 2900.
28 Cosmic Visions Workshop March 23, 2017
Skipper CCD - electron recoil background requirements A more detailed analysis: Klein-Nishina + binding energy correction
at lower energies atomic binding energies are relevant partial energy depositions populate low E region (thin det)
E [keV] 20 40 60 80 100 120 140 160 180 200 220 #events per bin 0.05 0.1 0.15 0.2 0.25
10 ×
sb:E {E<2000} 29 Cosmic Visions Workshop March 23, 2017
Skipper CCD - electron recoil background requirements A more detailed analysis: Klein-Nishina + binding energy correction
at lower energies atomic binding energies are relevant partial energy depositions populate low E region (thin det)
E [keV] 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 #events 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16 0.18 0.2
10 ×
sb:E {E<2} 29 Cosmic Visions Workshop March 23, 2017
Skipper CCD - electron recoil background requirements A more detailed analysis: Klein-Nishina + binding energy correction
at lower energies atomic binding energies are relevant partial energy depositions populate low E region (thin det)
E [keV]
10
10
10 1 10
2
10 #events 0.05 0.1 0.15 0.2 0.25 0.3
10 ×
29 Cosmic Visions Workshop March 23, 2017
Skipper CCD - electron recoil background requirements A more detailed analysis: MC simulation, G4 3D Monash model
at lower energies atomic binding energies are relevant partial energy depositions populate low E region (thin det)
E [keV] 50 100 150 200 250 #events per 10 eV bin 200 400 600 800 1000 1200
E*1000 {E*1000<250} 30 Cosmic Visions Workshop March 23, 2017
Skipper CCD - electron recoil background requirements A more detailed analysis: MC simulation, G4 3D Monash model
at lower energies atomic binding energies are relevant partial energy depositions populate low E region (thin det)
E [keV] 0.5 1 1.5 2 2.5 3 3.5 4 #events per 10 eV bin 200 400 600 800 1000 1200
E*1000 {E*1000<250} 30 Cosmic Visions Workshop March 23, 2017
Skipper CCD - electron recoil background requirements A more detailed analysis: MC simulation, G4 3D Monash model
at lower energies atomic binding energies are relevant partial energy depositions populate low E region (thin det)
E [keV] 0.1 0.2 0.3 0.4 0.5 #events per 10 eV bin 200 300 400 500 600 700 800 900 1000
E*1000 {E*1000<250} 30 Cosmic Visions Workshop March 23, 2017
Skipper CCD - electron recoil background requirements A more detailed analysis: MC simulation, G4 3D Monash model
at lower energies atomic binding energies are relevant partial energy depositions populate low E region (thin det)
E [keV] 0.1 0.2 0.3 0.4 0.5 #events per 10 eV bin 200 300 400 500 600 700 800 900 1000
E*1000 {E*1000<250} 31 Cosmic Visions Workshop March 23, 2017
Readout stage design
Summing well Output gate Floating gate Dump gate Dump drain
32 Cosmic Visions Workshop March 23, 2017
Electron density-of-states (1509.1598)
33 Cosmic Visions Workshop March 23, 2017
CCD: readout - typical operation for rare events searches
Clean the CCD Wait 30000s (~8.3 hs) Read - exposure with hits Read - blank (0s exposure) We take long exposures to minimize the number of readouts. The exposure is eventually limited by the dark current. The blank images provide an excelent measurement of the background produced by readout
The number of real events (produced by particles) scales with the total exposure time. The number of fake events (product of readout noise) scale with the number of readings (images taken). It is better to read as few times as possible.
34 Cosmic Visions Workshop March 23, 2017
Status of the experiments DAMIC
WIMP Mass / GeV c 1 10
2
WIMP-nucleon cross-section / cm
10
10
10
10
10
10
10
10
CDMS-II Si - 140 kg d CDMSLite - 70 kg d DAMA/Na LUX - 14 ton d CRESST II 2015 - 52 kg d
0.6 kg d arxiv:1607.07410
Eng WIMP search: 1607.07410 Fully commissioned Jan-17
CONNIE
R [events/day/kg] 30 25 20 10 5 15 10 1 0.1 0.01 0.001 Energy threshold [keV] Ethr = 50eV 12.8 evts/day/kg 35
Eng run: 1604.01343 Fully commissioned Aug-16 Both searches are limited by the readout noise of the sensors Very limited electron-recoil sensitivity: threshold ∼10e−
35 Cosmic Visions Workshop March 23, 2017
Raw image taken with SENSEI: 20 samples per pixel
OVERSCAN empty pixels (baseline) EXPOSED IMAGE X-rays & cosmics (for calibration)
36 Cosmic Visions Workshop March 23, 2017
Raw image taken with SENSEI: 20 samples per pixel
OVERSCAN empty pixels (baseline) EXPOSED IMAGE X-rays & cosmics (for calibration)
1 3 2 20 ONE pixel, 20 samples 36 Cosmic Visions Workshop March 23, 2017
Raw image taken with SENSEI: 20 samples per pixel
1 3 2 20 1 3 2 20
OVERSCAN empty pixels (baseline) EXPOSED IMAGE X-rays & cosmics (for calibration)
1 3 2 20 ONE pixel, 20 samples 1 3 2 20 1 3 2 20 baseline per line per sample 36 Cosmic Visions Workshop March 23, 2017
Image taken with SENSEI: 20 samples per pixel Single pixel distribution: X-rays from 55Fe
20 40 60 80 100 120 140 160 3700 3800 3900 4000 4100 4200
First sample Second sample
th
20 Pixel Sample Value (ADU) Counts per bin
The gain is the same for all the samples
37 Cosmic Visions Workshop March 23, 2017
55Fe X-ray source
38 Cosmic Visions Workshop March 23, 2017
55Fe X-ray source
38 Cosmic Visions Workshop March 23, 2017
keep counting: ..1575, 1576, 1577..
39 Cosmic Visions Workshop March 23, 2017