The MAJORANA Project

1
The MAJORANA Project

• Science of ??
• MAJORANA Demonstrator
• Detailed description
• Some technical issues
• Toward a 1-ton Experiment

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What is ???
Fig. from Deep Science
Fig. from arXiv0708.1033
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???and the neutrino

• ??(0?) decay rate proportional to neutrino mass
• Most sensitive technique (if Majorana particle)
• Decay can only occur if Lepton number
  conservation is violated
• Leptogenesis?
• Decay can only occur if neutrinos are massive
  Majorana particles
• Critical for understanding incorporation of mass
  into standard model
• ???is only practical experimental technique to
  answer this question
• Fundamental nuclear/particle physics process

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bb Decay Rates
G are calculable phase space factors. G0n
Q5 M are nuclear physics matrix elements. Hard
to calculate. mn is where the interesting
physics lies.
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Past Results
Elliott Vogel Annu. Rev. Part. Sci. 2002 52115
48Ca gt5.8x1022 y lt(3.5-22) eV
76Ge gt1.9x1025 y lt0.35 eV
76Ge gt1.6x1025 y lt(0.33-1.35) eV
76Ge 1.2x1025 y 0.44 eV
82Se gt2.1x1023 y lt(1.2-3.2) eV
100Mo gt5.8x1023 y lt(0.6-2.7) eV
116Cd gt1.7x1023 y lt1.7 eV
128Te gt7.7x1024 y lt(1.1-1.5) eV
130Te gt3.0x1024 y lt(0.41-0.98) eV
136Xe gt4.5x1023 y lt(1.8-5.2) eV
150Nd gt1.2x1021 y lt3.0 eV
CURE
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A Recent Claimhas become a litmus test for
future efforts
??? is the search for a very rare peak on a
continuum of background. 70 kg-years of
data 13 years The feature at 2039 keV is
arguably present.
NIM A522, 371 (2004)
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Future Data Requirements

• Why wasnt this claim sufficient to avoid
  controversy?
• Low statistics of claimed signal - hard to repeat
  measurement
• Background model uncertainty
• Unidentified lines
• Insufficient auxiliary handles
• Result needs confirmation or repudiation

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KKDC Claim
50 meV Or 1027 yr
Atmospheric Scale
Inverted
Solar Scale
Normal
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An Ideal ExperimentMaximize Rate/Minimize
Background

• Large Mass ( 1 ton)
• Large Q value, fast bb(0n)
• Good source radiopurity
• Demonstrated technology
• Ease of operation
• Natural isotope
• Small volume, source detector
• Good energy resolution
• Slow bb(2n) rate
• Identify daughter in real time
• Event reconstruction
• Nuclear theory

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Background Considerations
At atmospheric scale, expect a signal rate on the
order of 1 count/tonne-year

• ??(2?)
• natural occurring radioactive materials
• neutrons
• long-lived cosmogenics

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The usual suspects

• ??(2?)
• For the current generation of experiments,
  resolutions are sufficient to prevent tail from
  intruding on peak. Becomes a concern as we
  approach the ton scale
• Resolution, however, is a very important issue
  for signal-to-noise
• Natural Occurring Radioactive Materials
• Solution mostly understood, but hard to implement
• Great progress has been made understanding
  materials and the U/Th contamination,
  purification
• Elaborate QA/QC requirements
• Future purity levels greatly challenge assay
  capabilities
• Some materials require levels of 1?Bq/kg or less
  for ton scale expts.
• Sensitivity improvements required for ICPMS,
  direct counting, NAA

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As we approach 1 cnt/ton-year,a complicated mix
emerges.

• Long-lived cosmogenics
• material and experimental design dependent
• Minimize exposure on surface of problematic
  materials
• Development of underground fabrication
• Neutrons (elastic/inelastic reactions,
  short-lived isotopes)
• (?,n) up to 10 MeV can be shielded
• High-energy-? generated n are a more complicated
  problem
• Depth and/or well understood anti-coincidence
  techniques
• Rich spectrum and hence difficult at these low
  rates to discern actual process, e.g. (n,n?)
  reactions - which isotope/level
• Simulation codes are imprecise wrt low-energy
  nuclear physics
• Low energy nuclear physics is tedious to
  implement and verify

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1-ton Ge - Projected Sensitivity vs. Background
Goal is to achieve ultra-low backgrounds of less
than 1 count per ton of material per year in the
ROI about the bb(0n) Q-value energy.
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MAJORANA
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MAJORANA Collaboration Goals

• Actively pursuing the development of RD aimed at
  a 1 tonne scale 76Ge 0???-decay experiment.
• Technical goal Demonstrate background low enough
  to justify building a tonne scale Ge experiment.
• Science goal build a prototype module to test
  the recent claim of an observation of 0???. This
  goal is a litmus test of any proposed technology.
• Work cooperatively with GERDA Collaboration to
  prepare for a single international tonne-scale Ge
  experiment that combines the best technical
  features of MAJORANA and GERDA.
• Pursue longer term RD to minimize costs and
  optimize the schedule for a 1-tonne experiment.

Support As a RD Project by DOE NP NSF PNA
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The MAJORANA DEMONSTRATOR Module
76Ge offers an excellent combination of
capabilities sensitivities.
(Excellent energy resolution, intrinsically clean
detectors, commercial technologies, best 0???
sensitivity to date)

• 60-kg of Ge detectors
• 30-kg of 86 enriched 76Ge crystals required for
  science goal 60-kg for background sensitivity
• Examine detector technology options focus on
  point-contact detectors for DEMONSTRATOR
• Low-background Cryostats Shield
• ultra-clean, electroformed Cu
• naturally scalable
• Compact low-background passive Cu and Pbshield
  with active muon veto
• Agreement to locate at 4850 level at Sanford Lab
• Background Goal in the 0????peak ROI(4 keV at
  2039 keV)
• 1 count/ROI/t-y (after analysis cuts)

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MAJORANA DEMONSTRATOR Overview
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MAJORANA DEMONSTRATOR Module Sensitivity

• Expected Sensitivity to 0???(30 kg enriched
  material, running 3 years, or 0.09 t-y of 76Ge
  exposure)
• T1/2 ? 1026 y (90 CL).Sensitivity to ltm?gt lt 140
  meV (90 CL) Rod05,err.

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Cosmogenic 68Ge and 60Co
288d
68Ge
68Ga
68Zn
2.9 MeV
68Ge and 60Co are the dangerous internal
backgrounds For 60-kg enriched detector,
initially expect 60 68Ge decays/day. t1\2 288
d Minimize exposure on surface during enrichment
and fabrication PSD, segmentation, time
correlation cuts are effective at reducing these
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Point Contact Detectors
Hole vdrift (mm/ns) w/ paths, isochrones
Barbeau et al., JCAP 09 (2007) 009 Luke et al.,
IEEE trans. Nucl. Sci. 36 , 926(1989).
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Point Contact Detectors
Realization that a design based on commercial
BEGe detectors might be advantageous.
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Front End Electronics
Pulse Reset
Resistive Feedback
COGENT front ends (U Chicago)
UW Hybrid Design
LBNL Design
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String Designs
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First Module

• 18 natural-Ge Canberra BEGes on order
• Ø 702.5 mm, h 302.5 mm
• 579 g active mass
• contact r lt 6.5 mm (5 mm nom.)
• Front surface metalized for HV
• 4 to 6 crystals per string
• Front-ends mounted next to the crystal
• Closed cold plate and beefier Cu in detector
  mounts for added strength

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Shield Design
Side View
Top View
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Sanford Lab Layout - Draft
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Alternative Separation of 76Ge

• Demonstrator needs roughly 50 kg of 76Ge
• Russian centrifuge separation is the project
  baseline at 60/g
• ECP of Zelenogorsk supplied all the isotope for
  IGEX and HM experiments
• Evaluated possible alternative methods for
  separation
• thermal diffusion enrichment (SBIR developed -
  ready for test run)
• acoustic enrichment (immature)
• plasma enrichment (promising)
• UCLA spinoff, Nonlinear Ion Dynamics (NID),
  developing plasma separation isotope business -
  NIH funded development of machine for 18O
  production
• Majorana has contracted NID to produce a report
  and 76Ge material sample

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Electroforming and Cu Purity - Material purity

• Copper Cleanliness
• Assay data indicates that CuSO4 in bath is source
  of Th in part
• Producing our own CuSO4 from pure starting
  materials has been more successful in producing
  clean Cu then re-crystalizing the CuSO4.
• Initial ICPMS study in 2005
• 5-10 mBq/kg, limitation in materials, prep
• Improved to 2-4 mBq/kg
• Goal lt1 mBq/kg

• Copper Production
• Plating to several cm without machining
• Presently plating 2-5 mil/day
• Developing configurations, waveforms, recipes to
  improve buildup rate
• Purity limitations vs. buildup rate will come
  from 228Th tracer studies.

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Underground electroforming at WIPP - Cu purity

• Electroform a part underground
• Electroformed Cu is extremely pure, very little
  Th/U. By electroforming UG, the cosmogenic
  isotope Co-60 should be eliminated also
• Demonstrate that one can safely form a part
  underground in a highly regulated environment
• WIPP follows a strict safety protocol directed
  by DOE and MSHA
• Low voltage system to plate Cu from 1.2 M acid
  solution onto SS mandrel

Test Part Copper Beaker fabricated 660 gm 160
mm high, 110 mm diameter Wall thickness 1
mm 10 days of UG electroforming in two
stretches Solution is 1.5 kg copper sulfate
dissolved in 16 L 1.2M sulfuric acid Part
removed from mandrel by successive dunks in
boiling water and liquid nitrogen
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Low-background cryostat testing at WIPP - Large
cryostats

• Progress in the MEGA cryostat
• Installed and operated Ge detectors underground
  at WIPP in low-background apparatus
• Installed Ge detectors in clean room environment
• Connected and tested associated electronics
• Brought system to vacuum and cooled with LN
• Collected 17-hour background run from three Ge
  detectors

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Test Cryostat for String Design - Large cryostats

• Detector String
• Cryostat holds 3 strings - Each string holds 3
  detectors
• Strings hang inside detector hanger
• Goals
• Study thermal properties of the Majorana crystal
  cooling design
• Explore detector string design and mounting
  options
• Operate a string of cooled detectors under vacuum

• Thermal Test
• Stainless steel detector blanks (above) similar
  thermal mass and emissivity of Ge crystals
• Thermocouples mounted on blanks and copper parts
  show temperature response when cooled (above)
• Successful cooling of blanks by weak conduction

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HI?S FEL Runs to Characterize SEGA -
background/detectors
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Reference Design Backgrounds

• Background modeling
• Simulated major background sources for detector
  components in a 57-cystal array shield using
  MaGe
• Calculated total backgrounds individually for
  each detector technology under consideration
• Results
• Cu purity of 0.3 mBq/kg is required sizeable
  contribution from 208Tl in the cryostat and
  shield.
• Higher rejection of segmented designs is roughly
  balanced by introduction of extra readout
  components.
• P-PC appears to achieve the best backgrounds with
  minimal readout complexity.

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Better Sensitivity New Backgrounds
Pb target in neutron beam arXiv0809.5074

• Specific Pb gamma rays are problematic
  backgrounds
• 206Pb has a 2040-keV ? ray
• 207Pb has a 3062-keV ? ray
• 208Pb has a 3060-kev ? ray
• Neutron interactions in Pb can excite these
  levels
• The DEP of the 3062 keV ? ray is a single site
  energy deposit at ßß Q-value

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ORCA Object-Oriented Real-time Control and
AcquisitionHowe et al. IEEE Transactions on
Nuclear Science, 51 (3), 878-83

• Features
• Run time configuration, on-the-fly configurable
  acquisition tasks, run control, data monitoring,
  data replay capabilities, ROOT support.
• Real-time data stream can be broadcast to remote
  applications/machines
• Supports operator and expert user modes
• Object-oriented throughout (Objective-C), very
  modular, very easy to add new objects
• Uses XML for file headers and configuration
  storage
• Hardware Support
• VME, CAMAC, GPIB, cPCI, USB, IEEE 1394, Serial
• Usage
• SNO NCD, KATRIN pre-spect., CENPA accelerator,
  CENPA test stands, UW Radiology,
  MAJORANA(development), LANL, FZK test stands

Object Catalog
Drag n Drop to Place Objects
Configuration View
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MAJORANA - GERDA

• Bare enrGe array in liquid argon
• Shield high-purity liquid Argon / H2O
• Phase I (late 2009) 18 kg (HdM/IGEX diodes)
• Phase II (mid 2009) add 20 kg new detectors -
  Total 40 kg

• Modules of enrGe housed in high-purity
  electroformed copper cryostat
• Shield electroformed copper / lead
• Initial phase RD demonstrator module Total 60
  kg (30 kg enr.)

• Joint Cooperative Agreement
• Open exchange of knowledge technologies (e.g.
  MaGe, RD)
• Intention is to merge for 1 ton exp. Select best
  techniques developed and tested in GERDA and
  MAJORANA

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The MAJORANA Collaboration (Feb. 2009) Note Red
text indicates students
Black Hills State University, Spearfish, SD Kara
Keeter Duke University, Durham, North Carolina ,
and TUNL James Esterline, Mary Kidd, Werner
Tornow Institute for Theoretical and
Experimental Physics, Moscow, Russia Alexander
Barabash, Sergey Konovalov, Igor Vanushin,
Vladimir Yumatov Joint Institute for Nuclear
Research, Dubna, Russia Viktor Brudanin, Slava
Egorov, K. Gusey,Oleg Kochetov, M. Shirchenko,
V. Timkin, E. Yakushev Lawrence Berkeley
National Laboratory, Berkeley, California andthe
University of California - Berkeley Mark Amman,
Marc Bergevin, Yuen-Dat Chan, Jason Detwiler,
Brian Fujikawa, Kevin Lesko, James Loach, Paul
Luke, Alan Poon, Gersende Prior, Craig Tull, Kai
Vetter, Harold Yaver, Sergio Zimmerman Los
Alamos National Laboratory, Los Alamos, New
Mexico Steven Elliott, Victor M. Gehman, Vincente
Guiseppe, Andrew Hime, Kieth Rielage, Larry
Rodriguez, Jan Wouters North Carolina State
University, Raleigh, North Carolina and
TUNL Henning Back, Lance Leviner, Albert
Young Oak Ridge National Laboratory, Oak Ridge,
Tennessee Jim Beene, Fred Bertrand, Thomas V.
Cianciolo, Ren Cooper, David Radford, Krzysztof
Rykaczewski, Robert Varner, Chang-Hong Yu
Osaka University, Osaka, Japan Hiroyasu Ejiri,
Ryuta Hazama, Masaharu Nomachi, Shima Tatsuji
Pacific Northwest National Laboratory,
Richland, Washington Craig Aalseth, James Ely,
Tom Farmer, Jim Fast, Eric Hoppe, Brian
Hyronimus, Marty Keillor, Jeremy Kephart, Richard
T. Kouzes, Harry Miley, John Orrell, Jim Reeves,
Bob Thompson, Ray Warner Queen's University,
Kingston, Ontario Art McDonald University of
Alberta, Edmonton, Alberta Aksel
Hallin University of Chicago, Chicago,
Illinois Phil Barbeau, Juan Collar, Nicole
Fields, Charles Greenberg, University of North
Carolina, Chapel Hill, North Carolina and
TUNL Melissa Boswell, Padraic Finnerty, Reyco
Henning, Mark Howe, Michael Akashi-Ronquest,
Sean MacMullin, Jacquie Strain, John F.
Wilkerson University of South Carolina,
Columbia, South Carolina Frank Avignone, Richard
Creswick, Horatio A. Farach, Todd
Hossbach University of South Dakolta,
Vermillion, South Dakota Tina Keller, Dongming
Mei, Chao Zhang University of Tennessee,
Knoxville, Tennessee William Bugg, Yuri
Efremenko University of Washington, Seattle,
Washington John Amsbaugh, Tom Burritt, Peter J.
Doe, Jessica Dunmore, Robert Johnson, Michael
Marino, Mike Miller, Allan Myers, R. G. Hamish
Robertson, Alexis Schubert, Tim Van Wechel
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DEMONSTRATOR Schedule
2015
Begin construction of 1-tonne
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Summary

• Primary focus is on first module, 18 BEGes
• Much design work and prototyping in progress.
• Final detector mount / cryostat design and
  readout down-select for first module in the
  summer
• Sanford Lab preparations are proceeding rapidly,
  hope to begin installation late 2009
• Next collaboration meeting June 2-4 at Sanford
  Lab in South Dakota

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• EXTRAS

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MAJORANA technical progress - past year

• Materials Assay - Samples of low-activity
  plastics and cables have been obtained for
  radiometric counting and neutron activation
  analysis. Additional improvements have been
  gained in producing pure Cu through
  electroforming at PNNL and we have established an
  operating pilot program demonstrating
  electroforming underground at WIPP.
• Ge Enrichment - Options available for germanium
  oxide reduction, Ge refinement, and efficient
  material recycling were considered. We have a
  plan to develop this capability located near
  detector fabrication facilities in Oak Ridge. 
• Detectors - Additional p-type point contact (PPC)
  detectors have been ordered, using FY08 DUSEL RD
  funds as well as LDRD or institutional funds. 18
  of these detectors are intended for the first
  cryostat. Efforts to deploy a prototype
  low-background N-type segmented contact (NSC)
  detector using our enriched SEGA crystal are
  underway.  This will allow us to test low-mass
  deployment hardware and readout concepts while
  working in conjunction with a detector
  manufacturer. 
• Cryostat Modules - A realistic prototype
  deployment system has been constructed at LANL. 
  Modifications to this design are in place to
  permit prototyping of the current string design.
• DAQ Electronics Decision to use GRETINA
  digitizers. Preparing to place order. The slow
  control systems were exercised in a prototype
  deployment system at LANL.
• Facilities - Designs for an underground
  electroforming facility at the 800 level and a
  detector laboratory located on the 4850 level in
  the Homestake Mine are nearly complete in
  collaboration with the Sanford Laboratory design
  team. The schedule indicates the labs should be
  ready near the end of CY2009.
• Simulations - Several papers describing
  background studies have been published.
• Management - Task specific groups have been
  formed based on revised RD WBS.  Task leaders
  and their deputies have organized and held a
  number of workshops including Level 2 Task
  Leaders (Berkeley), Sanford/DUSEL planning (Lead,
  SD), Ge Enrichment (Oak Ridge), Cryostat Module
  (Seattle, Berkeley), Materials and Assay
  (Berkeley), and PPC Detectors (Oak Ridge). GERDA
  and MAJORANA collaborators have been attending
  the other collaborations meetings and updated
  the letter of intent to collaborate on a
  tonne-scale experiment.

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Refinements to the MAJORANA Demonstrator

• Concentrate on P-PC Detectors.
• Advantages of cost and simplicity, with no loss
  of physics reach.
• Will continue N-SC RD utilizing SEGA crystal.
• Considering additional physics one can do with
  low-energy P-PC detectors.
• exploits low-energy sensitivity (100 eV
  threshold) of P-PC detectors
• In joint partnership with agencies and
  institutions, plan early implementation of
  natural Ge P-PC sub-module.
• Future commitments of institutional funds
  dependent on agency support.

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The need for enriched 76Ge

• Background Risks
• Achieving acceptable backgrounds in natGe
  detectors is a necessary, but not a sufficient
  condition to demonstrate our background goal
• Past examples of significant background
  differences between natural and enriched
  detectors
• Require backgrounds a factor of 100 below
  previous Ge experiments
• At such levels, previously unanticipated
  background sources can arise
• Require 60 kg of total Ge to establish background
  goal
• 50 needs to be enriched to assure comparable
  background levels 30 kg enrGe
• Enrichment and purification can introduce
  impurities and physical differences that can
  impact subsequent chemistry
• Require intrinsic enrGe detectors with isotopes
  of U and Th at the 10-15 g/g
• Different isotopes of Ge have different
  cross-sections for cosmogenic activation
• Cost Risks
• Must develop and maintain separate production
  capabilities for reduction of GeO2 to Ge metal
  refinement to high purity Ge suitable for
  detector fabrication successful detector
  fabrication
• For 1-tonne it may be necessary to perform some
  of these steps UG
• Conclusion Must show in the Demonstrator phase
  that we can produce working enriched HPGe
  detectors with acceptable backgrounds.

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Point contact Detectors
Detectors in hand

• ORTEC PPC prototype gt500 g
• Canberra BEGe for low-BG low-E studies
• Inverted-coax PPC
• Mini-PPCs for surface preparation studies

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Front Ends Resistive Feedback

• Trace proximity provides 1 pF capacitance
• Silica or sapphire substrate provides thermal
  control
• Amorphous Ge resistor deposit in H environment
  gives proper R at low T
• MX-120 FET
• Possibility to add decoupling C inside feedback
  loop (substrate stands off HV)

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Front Ends Pulsed Reset
COGENT front ends
UW Hybrid Design

• Front-end and first stage hybrid design close
  the loop near the detector
• Power dissipation and radioactivity levels may be
  challenging
• Currently prototyping

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