a ssay and a cquisition of r adiopure m aterials

DUSEL Experiment Development and Coordination (DEDC)Internal Design Review

July 16-18, 2008Steve Elliott, Derek Elsworth, Daniela Leitner, Larry Murdoch, Tullis C. Onstott and Hank Sobel

Homestake DUSEL Initial Suite of ExperimentsDUSEL Experiment Development and Coordination

Assay and Acquisition of Radiopure Materials

Craig AalsethDonald AbrahamGary A. AndersonHenning BackTim ClassenJodi Cooley-SekulaPriscilla Cushman *Jason DetwilerYuri EfremenkoBrian FujikawaReyco Henning

Eric HoppeTina KellerRobert McTaggartDongming MeiAndreas PiepkeMark L. PittRichard SchneeTom SchumacherJohn Wilkerson

* Working Group Leader


Science

Cost Efficient Sharing of

Screening Detectors Cu electroforming Expert Personnel Materials Databases Simulation Software Characterization tools

Promote and foster

Cross-cutting applications New Assay Techniques Training and Education

A Dedicated Facility for the Assay, Control, and Production of Low Radioactivity Materials has been recognized as an essential shared task from the beginning of the DUSEL process.


Science

• Necessary Component to Neutrinoless Double Beta Decay

Dark Matter SearchesSolar Neutrino

• Creates new research opportunities in Radiation Biology

Microbiology and ExtremophilesCircuit manufactureGeology and hydrologyArchaeologyHomeland Security


Gamma Screening

Surface or 300’ level (~1 mBq/kg) a) Commercial HPGe

b) pre-screeners

c) NAA screeners

d) E&O, archaeology, local users…

4850’ facility ( ~0.1 mBq/kg) a) Bank of sensitive, shielded HPGe

(both planar and well)

b) For dark matter, double beta decay, solar neutrinos

c)Sensitive (TBD) applications in microbio, geology, security

Ultralow Facility (0.1 - 10 μBq/kg) a) Coincident HPGe at 4850’

b) Next generation large liquid scintillation counting at 7000’


Gamma Screening

Standard HPGe

Coincident Counting

4850-ft level (EIE)


Neutron Activation Analysis

– Transmute stable isotope (impurity) into a short lived radioactive isotope through neutron capture

– Neutron activation via a nuclear reactor (in general)

– Search for activated isotope decay by identifying signature gamma through gamma ray spectroscopy

Example:232Th + n 233Th(t1/2=22m)

e- + 233Pa(t1/2=27d) e- + 233U(t1/2=1.6E5y) + γ



Sample preparation– Any uranium, thorium, or potassium in or on the sample

will activate and be counted– Creating clean samples requires clean chemistry facilities

with hoods for working with acids (wet lab).

Radiochemical Neutron Activation Analysis– It is possible to further increase the sensitivity of NAA by

isolating the target isotope after irradiation.– Requires radiochemistry: dedicated wet chemistry area

with hood for handling solvents and acids needed for ion exchange chemistry

Dedicated HPGe at 300’ or surface



• Sensitivities are largely driven by counting times.

Element Parent Isotope

Product Isotope and Decay chain Gamma energy (keV)

Sensitivity

K 41K 42K (t1/2=12.26 hr) 1524 Best limit 0.1ppbTypical 5 ppb

U 238U 239U (t1/2 = 24 min) 239Np (t1/2 = 2.35d) 106, 222, 228, 277

Best limit 0.02 pptTypical 5 ppt

Th 232Th 233Th (t1/2 = 22 min) 239Pa (t1/2 = 27d) 312 Best limit 0.02 pptTypical 5 ppt


Beta Screening

Commercial standard is liquid scintillation counters with backgrounds ~ few per hour (1 at surface or 300’ level)

Better beta screening needed by– Dark matter experiments: CDMS & Edelweiss limited by beta

contamination (mostly 210Pb from radon) on surface or in thin films of detectors

– Radioisotope dating with beta sources competitive with AMS 14C/12C to 10-18, 3H/H to 10-20 also 10Be, 210Pb, 36Cl

– Low-level tracers for uptake and transport in biological studies

3 Large gas chambers shielded at 4850’ should screen to ~1 / m day– Drift chamber (DUSEL R&D funded

project “BetaCage”)– Cloud chamber– Ideal for alpha screening, too


Beta Screening

Modest Infrastructure

1. Bkgd dominated by external , clean copper, lead, or large water shield

2. Rn-free sample loading

3. Gas handling


Alpha Counting

• Current alpha counting sensitivity limited to ~ 0.1 /cm2-day – large area wire chambers (~1000 cm2) or small (~10 cm2) Si detectors.– Not competitive with gamma for bulk U and Th activity, confined to niche

areas-- investigation of surface contamination and isotopes with no associated gamma activity, especially 210Po (a radon daughter).

• Improvement by x100 in sensitivity seems achievable.– Goal: 1000 cm2 device with 1 count per day background.– Commercially available 1800 cm2 ion chamber (XIA) is promising.

• limited by internal contamination, should be possible to fix.– Reaching 0.001 /cm2-day would allow exploration of surface contamination

• CDMS, currently ~0.003/ cm2-day• COUPP, ~0.8/ cm2-day• Others…?

• Main requirements for counting facility are– Class 100 clean room space– Sample cleaning equipment: ultrasound, high purity water– Radon at level of normal surface air (~10 Bq/m3)


Radon Mitigation

Requirements for DUSELNeeds to be determined, depends onVolume of space that needs radon

reduced air or radon free gasAmount of make-up air in cleanroom Level of radon exisiting in cavernCavern-wide radon mitigation (ventilation)

Problems with RadonRadon is a daughter in both the 238U

and 232Th decay chainsCan cause backgrounds direct gamma

counting determination of U and ThDaughters of radon decay can plate-

out onto sensitive detector surfaces

Removing Radon Use radon free gases such as boil

off LN to obtain lowest possible level in detector volumes

When air is required: adsorb radon onto activated charcoal

Examples include:

Borexino cleanroom at Princeton

Super Kamiokande NEMO3 radon free tent

HPGe spectrum with gamma lines from the 238U decay chain. Probably due to 222Rn in the sample chamber


Radon emanation

• Radon emanates from materials due to radium contamination• Detection:

Sample material is sealed in an “emanation chamber” where radon builds up over time. Measured using standard radon detection methods:

Example of systems:– SNOlab has 8 electrostatic counters (I. Lawson, DUSEL Town Meeting, 2007)

Sensitivity = 5 - 10 atoms (222Rn) per day – MPIK in Heidelberg uses proportional counters (Astropart. Physics 18 (2002) 1)

Sensitivity = 1-5 atoms (222Rn) per day

• DUSEL requirements– Need to determine what is required by experiments.– Compare materials, sensitivities, vs HPGe– A single SNOlab chamber turn-around is one month


Mass Spec and other Techniques

• Need to evaluate what assay tools must be located underground and which can be sent off-site– Dedicated, extensive underground analytical lab likely needed due to

low-background and purity requirements• Best sensitivities can be submicro Bq/kg

• Based on a wide spectrum of analytes and anticipated sensitivity the current underground candidates likely are:– Inductively Coupled Plasma/Optical Emission Spectroscopy (ICP/OES)– Inductively Coupled Plasma/Mass Spectroscopy (ICP/MS)– Laser Ablation-ICP/MS– Secondary Ion Mass Spectrometry (SIMS)– Glow Discharge or Thermal Ionization Mass Spectroscopy

(GD/MS or TIMS)

• Also need chemistry/wet lab facilities to support the sample preparation/dissolution


Mass Spec and other Techniques

• Other Analytical tools likely to be needed underground– Optical Microscopy

– Scanning Electron Microscopy (SEM) with various electron excitation spectroscopies and electron backscatter

– Transmission Electron Microscopy (TEM)

– Scanning Tunneling Microscopy/Atomic Force Microscopy (STM or AFM)

• Physical Properties Testing– Hardness and tensile strength

– Grain size and orientation evaluation (from SEM and EBSD)


Cryogens

Most of Experiments will require Cryogens and Purified Gases

Example of Pure Nitrogen Generator installed at Kamioka: Productivity: 40Nm3/hr of N2

Levels of purity: 39Ar < 0.2 μBg/m3

85Kr << 1 μBg/m3

Rn < 3 μBg/m3

• Detectors, Coolants and/or Shielding for Dark Matter and Double Beta decay

• Coolants for Gamma Counting

• Radon Reduced gas for Clean rooms and Glove Boxes

Organizing their production (what we need to determine)• Footprint underground

• Supply of Gases and Electrical Power

• System of delivery to Experiments

• Staff for Operation and Maintenance


Electroforming Facility

• Ultra High Purity Copper is needed for a wide variety of experiments including those for the next generation of neutrino physics, dark matter, and material sciences– Submicro Bq/kg is now possible

• Must be electroformed underground to minimize cosmogenic in-growth of impurities and retain original crystal integrity

• Other materials may also require electroforming. The number of experiments needing the material and the material compatibility must be evaluated to determine appropriate facility requirements


Material Storage and Cleanliness

Detector/Shielding Storage (reduce cosmogenic activation) At least 300’ and Rn-free environment Pure Cu, Lead Shielding Common small parts (evaluate this possibility)

Purified Water Common purification plant (design facility) Common screening location (water shield)

Clean Machine Shop Determine Needs and Quality Assurance procedure

Determine boundaries between this S4, DM Infrastructure S4, and Facilities


Electroforming Facility

• Highest purity copper in the world to be produced

• Facilities will be extensive consisting of the main electroforming area, the cleaning/treatment area, and the storage area

• Cleanroom class 1000 for electroforming, class 100 for cleaning area

• Large quantities of acid sulfate electrolyte anticipated

• Extensively instrumented for process monitoring

Draw from recent design experience of similar Pacific Northwest National Lab space


Education and Outreach

• Undergraduates– Contributions to Site Characterization, summer jobs

• Graduate Students/Post-Docs– Training Opportunities

• In-service/Pre-service K-12 Teachers– Physics of Atomic Nuclei - Underground (SD Pilot Workshop – Summer 2008)– Development of Curriculum Materials based on SD State Standards – Annual visit to South Dakota: Math and Science teachers in January/February

• K-12 Students– Physics of Atomic Nuclei - Underground (include students - Summer 2009)– Native American serving high schools, tribal colleges

• Outreach– Sanford Center – Contribute exhibits to facility– 300 ft level – access to public, tours– Summer support for K-12 in-service/pre-service teachers to act as docents – Connection to Science on the Move program in SD

standard counting equipment (i.e., radiation monitors, cosmic ray detectors) curriculum development


Integrative Functions

• Enabling the Physics Experiments Full characterization of Homestake

Rock/water radio-isotopes, radon, neutron/muon flux

Scheduling tools Onsite Assay (managing common facility) Offsite samples (ICPMS, NAA Irradiation, Underground sites…)

Materials Database Simulation Software

Links to ILIAS JRA1, sharing expertise and info

• Creating the Larger User Community (Integrative website) Cross-disciplinary Workshops

some in common with “Cross-cutting group” Training Programs and Seminars

Collaborations and Proposals with Industry, ILIAS, Universities, Nat’l Labs


Schedule: Year 1

Design “Facility for AARM” (FAARM)Determine needs of ISE

Identify limited R&D required

Participate and plan SUSEL screening program EPSCoR, MRI, Donations from existing sites

Start Training program between SD and Kimballton/Soudan

Characterize the DUSEL environmentCompile all exisiting and historical data

Cavern U/Th/K (chemical and spectroscopy), Rn survey

Cross-calibrate with ILIAS (Jan Kiesel - standard survey)

Create AARM integrative group with websiteIntegrate with other S4 groups (DUSEL integration workshop)

Identify new user base (Synergies workshop -shared with cross- cutting S4 and E&O)


Schedule: Year 2

Design FAARM Design, schedule and implementation plan for FAARM

DUSEL AARM Workshop R&D on target opportunities Training (Schedule courses at SUSEL, invite participants)

Start SUSEL screening (part of staged DUSEL design)

Characterize the DUSEL environmentFinish initial surveys

Design/Implement longterm muon/high energy neutron monitoring

Design and cost overall Radon mitigation plan

Expand website functionalityCreate user interface for screening (incl. existing sites, ILIAS)

Create Materials Database and Software repository

Consolidate new user base (2nd Synergies workshop)


Schedule: Year 3

Complete FAARM design Finish design of DUSEL facility (DUSEL integration workshop)

Screening & Cu Electroforming proceeding at SUSEL Training Seminars at SUSEL

Maintain and Expand Integrative Website Screening schedules integrated between SUSEL and other sites

Include design plans from new user base (3nd Synergies workshop)


Budget: Year 1

Design “Facility for AARM” (FAARM)Project engineer (15 weeks) $100k

Video conferencing, supplies, etc $2k

Secretarial support $10k

Characterize the DUSEL environmentTravel to site (10 trips of 1 week each) $15k

1 mo. Summer salary (SD person?) $9k

Summer travel for others $10k

2 undergrads, 2 grads to help (E&0, collaborate with EPSCoR) $20k

Host Jan Keisel & staff (ILIAS) $30k

Create AARM integrative group with websiteSoftware engineering support $50k

DUSEL integration workshop $20k

Synergies workshop $25k


Budget: Year 2

Design FAARM Project engineer (15 weeks) $100k

DUSEL AARM Workshop $20k

R&D (not yet specified) $40k

Characterize the DUSEL environmentEngineering (Rn survey, mitigation) $30k

Muon and HE neutron system $30k




Expand website functionalitySoftware support $40k

2nd Synergies workshop $25k


Budget: Year 3

Complete FAARM design Project engineer (15 weeks) $100k

DUSEL integration workshop $20k




Maintain and Use Integrative Website Software support $30k

3nd Synergies workshop $25k


ISE Estimated Budget

Materials Assay

Materials Storage

Materials Processing

a ssay and a cquisition of r adiopure m aterials

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