SENSEI † first results, status and plans Guillermo Fernandez Moroni for the SENSEI Collaboration June 5, 2019 † S ub- E lectron- N oise S kipperCCD E xperimental I nstrument New Directions in the Search for Light Dark Matter Particles, June 4-7, 2019. 1
SENSEI: lower the energy threshold to look for light DM candidates Detect DM-e interactions by measuring the ionization produced by the electron recoils. See arXiv:1509.01598 Idea: use electrons in the bulk silicon from a CCD as target CCD pixel conduction band hole DM electron valence band Si + This requires very low noise! New Directions in the Search for Light Dark Matter Particles, June 4-7, 2019. 2
SENSEI Collaboration Build a detector using Skipper-CCDs to search for light DM canditates 50 Years of Discovery Fermilab: Michael Crisler, Alex Drlica-Wagner, Juan Estrada, Guillermo Fernandez, Miguel Sofo Haro, Javier Tiffenberg Oregon University: Tien-Tien Yu Stony Brook: Rouven Essig Tel Aviv University: Liron Barack, Erez Ezion, Tomer Volansky + several additional students + more to come Fully funded by Heising-Simons Foundation & Fermilab New Directions in the Search for Light Dark Matter Particles, June 4-7, 2019. 3
√ Noise vs. #samples - 1/ N New Directions in the Search for Light Dark Matter Particles, June 4-7, 2019. 4
protoSENSEI: technology demonstrator 1cm 2cm readout stages 200 um thick 0.1 gram mass We used the parasitically-fabricated R&D sensors to learn how to optimize operations and produce early-science results New Directions in the Search for Light Dark Matter Particles, June 4-7, 2019. 5
protoSENSEI: project timeline RO electronics optimization & integration characterization MINOS installation MINOS run start Jun16 Jan16 Jan17 Apr17 Clean-room Low rad. package Deploy at MINOS commissioning and data taking run at surface explore high xsec explore small xsec arXiv:1804.00088 arXiv:1901.10478 New Directions in the Search for Light Dark Matter Particles, June 4-7, 2019. 6
Current step: Prototype running @MINOS Technology demonstration: installation at shallow underground site NOvA NuMI building SENSEI 107 m MINOS Hall New Directions in the Search for Light Dark Matter Particles, June 4-7, 2019. 7
protoSENSEI @MINOS: raw image/data (70 min exposure) 200 pixels 370 pixels 0 1 e- 2 e- 3 e- or more adjacent pixels with one or more electrons are grouped together New Directions in the Search for Light Dark Matter Particles, June 4-7, 2019. 8
Results with Skipper CCD prototype (PRL 121, 061803; PRL 122, 161801) �� - �� �� - �� � ↑ | � � |= � 4 | = �� - �� 10 � | � � � � - � � � �� - �� � � � � � � � | � � |=| � � | � - � � � �� - �� �� - �� � � � � = � Exposure: 0.019 gram-days � � � � | � � � | � � - 3 �� - �� � � � � �� - �� 10 � � � � � � - � � � �� - �� � � - �� - �� �� - �� ������ � � =| � � | Entries 2 � � - 10 �� - �� �� - �� � | � = | � σ � [ �� � ] σ � [ �� � ] �� - �� � ������ �� - �� �� - �� � � - 10 �� - �� �� - �� � � - �� - �� | � � |=| � � | � � - �� - �� �� - �� 1 � � - ������� �� - �� �� - �� �������� �� - �� �� - �� �������� - �� �� - �� 10 -1 ������� 1 2 3 4 5 6 �� - �� �� - �� - Charge [e ] (a) First run event spectrum. �� - �� � �� =( α � � / � ) � � �� = � �� - �� �� - �� � �� �� � �� � �� � �� � � �� � χ [ ��� ] � χ [ ��� ] 6 10 periodic-readout 5 10 Exposure: 0.069 g day Events per 0.02 e - bin gaussian fit 4 10 10 3 10 2 10 1 -1 -0.5 0 0.5 1 1.5 2 2.5 3 3.5 4 - Charge [e ] (b) Sec. run event spectrum. (c) light mediator (d) heavy mediator New Directions in the Search for Light Dark Matter Particles, June 4-7, 2019. 9
protoSENSEI @MINOS: all the information, pick your model N e periodic continuous Cuts 1 2 3 3 4 5 1. DM in single pixel 1 0.62 0.48 0.48 0.41 0.36 2. Nearest Neighbour 0.92 0.96 3. Electronic Noise 1 ∼ 1 4. Edge 0.92 0.88 5. Bleeding 0.71 0.98 6. Halo 0.80 0.99 7. Cross-talk 0.99 ∼ 1 8. Bad columns 0.80 0.94 Total Efficiency 0.38 0.24 0.18 0.37 0.31 0.28 Eff. Expo. [g day] 0.069 0.043 0.033 0.085 0.073 0.064 Number of events 2353 21 0 0 0 0 New Directions in the Search for Light Dark Matter Particles, June 4-7, 2019. 10
What’s next? General timeline LDRD funded, testing of prototype, fabrication of SkipperCCD received funding from HSF prototype for SENSEI experiment early science from prototypes SENSEI at MINOS (~10 gr) and design and fabrication of commissioning at Snolab (~100 gr) SENSEI experiment analisis of SENSEI at Minos analisis of Snolab data and take data at Snolab New Directions in the Search for Light Dark Matter Particles, June 4-7, 2019. 11
New electronics (FNAL+IIIE effort) number of pixels final pixel value (adu) Scalable up to 1 kg of CCDs New Directions in the Search for Light Dark Matter Particles, June 4-7, 2019. 12
Science detectors arrived last week to Fermilab Already packaged and showing very good performance! New science is coming in the next weeks!!! New Directions in the Search for Light Dark Matter Particles, June 4-7, 2019. 13
Focus on measuring the ionization efficiency Alig model is incomplete and we are already measuring with skipper CCD using photons. New Directions in the Search for Light Dark Matter Particles, June 4-7, 2019. 14
BACK UP SLIDES New Directions in the Search for Light Dark Matter Particles, June 4-7, 2019. 15
Dark current measurements and expectation DC (e-/pix/day) 10 General purpouse CCD setups. No IR cover. At sea level. Output transistor ON. 1 SENSEI prototype surface run (low resistiv. Si) and CONNIE experiment (high resistiv. Si). ~IR cover. 10 -1 At sea level. Output transistor ON. 10 -2 SENSEI prototype run (low resistiv. Si). ~IR cover. 10 -3 At MINOS (100m underground). DAMIC experiment run (high resistiv. Si). ~IR cover. 10 -4 At SNOLAB (2km underground). Output transistor ON. SENSEI expectation 10 -5 with high resistivity Si. IR cover. At SNOLAB (2km underground).Output transistor OFF . 10 -6 10 -7 Theoretical expectation. Janesick, SPIE press, 2001. New Directions in the Search for Light Dark Matter Particles, June 4-7, 2019. 16
SENSEI: 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) missing energy γ e - ionization CCD New Directions in the Search for Light Dark Matter Particles, June 4-7, 2019. 17
SENSEI: 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) 5 DRU New Directions in the Search for Light Dark Matter Particles, June 4-7, 2019. 17
SENSEI: 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) 5 DRU New Directions in the Search for Light Dark Matter Particles, June 4-7, 2019. 17
SENSEI: 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) 5 DRU New Directions in the Search for Light Dark Matter Particles, June 4-7, 2019. 17
SENSEI: 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) Back of the envelope estimation is conservative 5 DRU New Directions in the Search for Light Dark Matter Particles, June 4-7, 2019. 18
Diffusion New Directions in the Search for Light Dark Matter Particles, June 4-7, 2019. 19
Hardware binning x3 x3 H 3 x3 H 2 H 1 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 sens node The optimal effective pixel size can be chosen by using hw binning µ sigle = R DC × ( T pix × n pix ) = µ binning = ( n bin × R DC ) × T pix × n pix / n bin � �� � � �� � � �� � Eff DC T expo T expo New Directions in the Search for Light Dark Matter Particles, June 4-7, 2019. 20
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