watchman: a water cherenkov monitor for antineutrinos ......the watchman collaboration 3 uc davis uc...

Defense Nuclear Nonproliferation

Lawrence Livermore National Laboratory Sandia National Laboratories

Adam Bernstein Lawrence Livermore National Laboratory May 01 2014 WATCHMAN Collaboration Meeting

1

WATCHMAN: a WATer CHerenkov Monitor for ANtineutrinos

Meeting Goals Project Status



Meeting Goals

Today Thursday May 1 •  Bring collaborators and guests up to date on WATCHMAN

scope and status of all tasks •  Discuss reactor and supernova physics, and large Cherenkov

detector R&D potential Tonight – Banquet at Sal’s Restaurant in Blacksburg Tomorrow Friday May 2 Morning: KURF Tour and talks for WATCHBOY/MARS detectors Afternoon: Review and discuss ISODAR beam physics Throughout Consider synergies with ISODAR, ANNIE, and other physics efforts

2

The WATCHMAN collaboration

3

UC Davis

UC Berkeley

UC Irvine

U of Hawaii

Hawaii Pacific

A. Bernstein, N. Bowden, S. Dazeley, D. Dobie

P. Marleau, J. Brennan, M. Gerling, K. Hulin, J. Steele, D. Reyna K. Van Bibber, K. Vetter, C. Roecker, T. Shokair R. Svoboda, M. Askins, M. Bergevin, Daine Danielson Students getting WATCHMAN-related Ph.D. s Undergraduate

J. Learned, J. Maricic S. Dye M. Vagins, M. Smy S.D. Rountree, B. Vogelaar, C. Mariani, Patrick Jaffke

World Leaders in the Development and Use of Large Water Cherenkov Detectors

2 Na;onal Laboratories 6 Universi;es 25 collaborators 15 physicists 5 engineers 2 Post-‐docs 3 Ph.Ds 1 Undergrad

We need to add collaborators if full project goes forward



Remote Reactor Monitoring is an NNSA Strategic Goal

4

§  Now: 3 year scoping project with 4 Tasks

§  2014-15 Decision point to deploy WATCHMAN, a kiloton scale antineutrino detector, ~10 km from a US reactor

§  Proposed joint funding with Office of Science, High Energy Physics (DOE-SC-HEP)

2015 Federal budget defers start to 2016 (we believe)



Top level view of schedule

A.  Low risk option, 2016 start: – 2015 Intermediate Design, continued KURF data-

taking – Conservative 4 year installation plan to reach

operational state – 2016-2019

B.  High risk option: October 2014 start: – Gd-H2O fill and partial instrumentation with 50% of

PMTs by December 2016 to observe reactor antineutrinos by the original Strategic Plan date

– Highly constrained schedule with no contigency

5



A budget-informed guess about project timing

6

Page 473



Post-WATCHMAN goal: find/exclude hidden 10 MWt reactors at up to ~1000 km

7

Goal

Detector target mass standoff

5 events in 1 year from a 10 MWt reactor (negligible background, 50% efficiency, includes oscillations) >99% exclusion if 0 events observed, 5 expected Zero false positive rate for zero expected, 5 observed

24,000 ton

100 km

2 Megaton

1000 km

Global reactor antineutrino fluxes simulation courtesy Jocher/Learned NGA/UH

•  Gadolinium-‐doped (light) water is the most viable option for scaling to the largest sizes

•  Strong synergy with fundamental physics research – Many groups/countries are already investing in this technology

•  SuperKamiokande is today’s largest comparable detector -‐ 50,000 tons of H2O

Science & Global Security, 18:127–192, 2010



WATCHMAN Technical Goals

1+4 year Construction and Operation Phase (2015, 2016-2019) •  Demonstrate sensitivity to reactor ON/OFF transition at ~10 km standoff, with

at most 30 days of ON and OFF data, with at least 99% confidence, with a kiloton scale detector.

•  Demonstrate innovative, scalable, cost-effective Gd-H2O Cherenkov technology, pioneered and patented by WATCHMAN collaborators

•  Provide a data-sharing and joint funding model for the scientific community to make use of antineutrino data from WATCHMAN and future nonproliferation detectors

8

3 year Scoping Phase (2012-2014) 1.  Consider Use and Gap Analysis 2.  Select a Site 3.  Create a Preliminary Design, Budget and Schedule 4.  Measure of Shallow Depth Backgrounds – October deliverable

May 19 deliverables



A new Task: study relevance for nonproliferation

•  Similar to other joint global nonproliferation and science efforts –  CTBT’s International Data Center regularly shares seismic

data with the science community (Intl. Science Ctr.) – infrasound and hydroacoustic also shared

–  The SESAME synchroton project in Jordan – “"SESAME…will serve as a beacon, demonstrating how shared scientific initiatives can help light the way towards peace” 45 Nobel Laureates

9

•  WATCHMAN will demonstrate a capability to exclude or discover undeclared reactors with high confidence in a wide geographical region

•  Small reactor 10 MWt standard: 4 kg Pu/year à 0.5 IAEA Significant Quantity •  New Task: Gap analysis for alternative technologies, use case for antineutrino monitor

–  Radionuclide sensing and satellites are the current open-source methods for reactor finding

–  Possible relevance to Treaties, Agreements, Confidence Building Measures is now being studied – Not relying only the Strategic Plan goal for justification



Preferred and Backup sites identified

10

Preferred Backup Reactor Location PERRY Reactor

Perry Ohio Advanced Test Reactor,

Idaho Falls, Idaho

Thermal Power (MWt) 3875 120

Detector Location Morton Salt/IMB mine (!) Painesville, Ohio

New excavation Idaho National Laboratory

Standoff 13 km - the only reactor in the US at a suitable distance from a deep mine

1 km

Overburden (mwe) 1430 ~360

Approval status Morton Salt has approved installation !

INL has approved excavation studies

Physics potential Greater physics potential due to greater depth



Antineutrino signal and background

11

n (100-‐200 MeV)

n

n

µ

µ

9Li β

Signal in 1 kiloton of water

n νe p

Σγ ~ 8 MeV

511 keV

511 keV e+

Gd

τ ~ 30 µs prompt e+ signal + n capture on Gd

•  Exactly two Cerenkov flashes •  within ~100 microseconds •  Within a cubic meter voxel

‘The antineutrino heartbeat’

Backgrounds: 1.  Real antineutrinos 2.  Random event pair coincidences 3.  Muon induced high energy neutrons 4.  Long-lived radionuclide decays



Full Signal and Background Monte Carlo using GEANT/RMSIM

12

Depth Dependent per day •  Fast Punch-through Neutrons ~1 •  Radionuclides à not well known ~1-10 Depth-Independent •  PMT and Rock Gamma/Neutrons <1 ?

Other Reactors <1 Geoantineutrinos negligible ___________________________________________ Total Background ~10 Perry Reactor Signal 8-12



Preliminary Design Task

13

•  Largest possible cylindrical tank at Morton - 3:1 kTon total:fiducial

•  Stainless tank, assembled in place

•  PMTs mounted on a frame in the tank. - 5500 Target PMTS looking “in” - 480 Veto PMTs on same frame looking “out”

Drift layout at Morton Salt Mine Close-up of Veto PMT Wall

78 feet



We’re not alone: other large water detector R&D

Detector EGADS WATCHMAN Hyper-K

Status Ongoing 2016 start 2021 start (approx.) Mass (ton) 200 1,000 - 10,000 560,000

Type Gd-WCD Gd-WCD Pure H2O or Gd-WCD

Purpose Measure background materials,energy threshold Too small to see reactor antineutrinos

Remotely detect reactor antineutrinos – beam and reactor physics potential

Neutrino oscillations, proton decay, supernovae… WATCHMAN would demonstrate Gd option for HyperK or other future big detectors

14



Physics Synergy WATCHMAN will provide: •  The U.S.’s only supernova watch detector

•  A demonstration of technologies for future large neutrino detectors (advanced PMTs, water-based scintillator…)

15

Requires nearby neutrino beam

Requires upgrade to scint.

DOE Office of Science co-investment is critical to the project’s success ‘Positive dual-use’ aspect strengthens the long term case for remote monitoring

WATCHMAN may also provide: •  a measurement of the ordering of the neutrino masses

– a major question for 21rst century physics

e,µ,τ•  A search tool for a proposed 4th neutrino flavor

( are the only currently known flavors) •  A search tool for non-standard neutrino interactions



Background Measurements at the Kimballton Underground Research Facility

16

•  Drive in access don to 1500 foot depth

•  First-‐ever continuous measurement as a function of depth

•  Most important at shallow depths (300 feet, alternative site)

•  Final measurement will be at the 1400 foot depth of preferred site Multiplicity and Recoil Spectrometer

for fast neutron energy spectrum

Small version of WATCHMAN (WATCHBOY) to measure muogenic radionuclide backgrounds

Time between muons in WATCHBOY

Entering KURF



Next Steps

May 2014: •  Provide detailed information to DNN as part of their

review process – May 27 review •  Generate white paper on WATCHMAN physics

potential for DOE Office of Science – submit full proposal

•  Summer 2014: Possible reference in HEP advisory committee long term planning report (‘P5 committee’)

October 2014: •  Publish first experimental results on depth

dependent backgrounds

17



Backup slides

18



Prior work and technical challenges

•  2004 KamLAND project: Japanese team demonstrates 400 km detection of reactor antineutrinos, but using an expensive and difficult-to-scale technology (oil-based liquid scintillator)

•  2012 LLNL DNN funded project – first-ever demonstration of time-tagged neutron detection in water (1 ton detector)

•  2014 EGADS project: WATCHMAN collaborator Vagins demonstrates long term recirculation/purification of 200 tons of Gd-doped water (engineering prototype, no antineutrino sensitivity)

•  All individual steps have been separately tested to high Technical Readiness: integration is the key technical challenge

19



Historical examples indicate that satellite imagery is a favored tool

20

Country(and(location(

Reactor(characteristics(

Discovered(before(

complete?(

NPT(party(at(the(time(of(

discovery?(

(obligated(to(have(declared(the(reactor(?(

How(was(the(reactor(discovered?(

DPRK,&Yongbyon& ~25&MWt& Yes& No& No& satellite&imagery&at&known&Yongbyon&facilityi&

Algeria,&Birine& 15&MWt&& Yes& No& No& news&article,ii&claims&construction&had&been&observed&in&satellite&imagery.&China&reportedly&notified&the&U.S.&of&its&intention&

to&supply&the&reactor.iii&Pakistan,&Khushab&

~50&MWt& Yes&?& No& No& Announced&by&Pakistan&in&April&1998,iv&but&open&sources&references&suggest&it&was&known&to&U.S.&intelligence&before&then.v&

Iran,&Arak& 40&MWt&& Yes& Yes& No& officially&announced&4Q2004&vi&Q&publicly&disclosed&by&NCRI&in&August&2002.vii&&U.S.&Intelligence&discovery&may&have&preceded&

that&date&Syria,&Dayr&Alzour& 25&MWt&?&& Yes& Yes& Yes& 4Q2008&DNI&briefing&showed&satellite&and&

ground&photography.viii&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&i&Don&Oberdorfer,The&Two&Koreas,&p.&25;&see&also&declassified&reports&at&http://www2.gwu.edu/~nsarchiv/NSAEBB/NSAEBB87/&&ii&Bill&Gertz,&Washington&Times,&11&April&1991.&iii&&Letter,&Ambassador&Richard&Kennedy&to&Editor&of&the&New&York&Times,&20&November&1991&(http://www2.gwu.edu/~nsarchiv/nukevault/ebb228/index.htm)&

iv&"Pakistan's(Indigenous(Nuclear(Reactor(Starts(Up,"(Islamabad,(The$Nation,(April(13,(1998.&v&Mark&Hibbs,&"Bhutto&May&Finish&Plutonium&Reactor&without&Agreement&on&Fissile&Stocks,”&Nucleonics&Week,&October&1994.&vi&Jeffrey&T.&Richelson,&Spying&on&the&Bomb,&p.&504&.&vii&National&Council&of&Resistance&on&Iran,&“Information&on&Two&Top&Secret&Nuclear&Sites&of&the&Iranian&Regime&(Natanz&and&Arak),”&pp.&1Q2&viii&"Background&Briefing&with&Senior&U.S.&Officials&on&Syria's&Covert&Nuclear&Reactor&and&North&Korea's&Involvement,"&Office&of&the&Director&of&National&Intelligence,&24&April&2008,&available&at&the&Council&on&Foreign&Relations&Website,&www.cfr.org.&&



Siting Study: Map of US Power Reactors

21



Siting Study: US Reactors + Active Mines

22



Two Possible Use Cases - Large Detectors

23

Exclusion: Ensure no reactors are operating at 10-1000 km standoff

Absence of undeclared reactors: ensure only declared reactors are

operating at a known site

Ø  Simplest scenario •  Searches for excess antineutrino

signal above background

Ø  Most sensitive •  Low background levels

Ø  Best suited to finding or excluding new reactors in areas without existing reactors

Ø  Potential countermeasures are

politically or financially costly •  Build a declared reactor near the

detector •  Physically attack the detector

Ø  More complex •  Requires knowledge of signal

from declared reactors

Ø  Higher backgrounds due to other reactors

Ø  Adjusting power of declared reactors is a potential countermeasure

We are not yet claiming significance for any particular Treaty or Agreement



Reactor Antineutrino Emissions

The famously low antineutrino interaction probability is good and bad

ü Detectable at long ranges ü Effectively impossible to falsify, disguise, or shield without another

reactor ☓ Requires big detectors for remote sensitivity

24

•  1021 fissions per second in a 3,000-MWt reactor

•  6 antineutrinos per fission from beta decay of neutron-rich daughters



Technical approach

•  For the first time: Use water Cherenkov technology to detect low-energy reactor antineutrinos (1-10 MeV).

•  0.1% doping with neutron capture agent Gadolinium provides good ’tagging’ efficiency for the neutron - essential for background rejection

•  High Quantum Efficiency PMTs enable sensitivity to the ~10-100 photoelectron signals arising from the positron and neutron created by antineutrino interactions on protons in water

25

νe + p à e+ + n

n νe p

Σγ ~ 8 MeV

511 keV 511 keV e+

Gd

τ ~ 30 µs prompt e+ signal + n capture on Gd

watchman: a water cherenkov monitor for antineutrinos ......the watchman collaboration 3 uc davis uc...

Documents