Overview on Radiopurity Juergen Reichenbacher DUNE Collaboration Meeting Rapid City, SD 05/20/2016

20-May-2016J. Reichenbacher (SDSM&T)2 OUTLINE 1.) Screening Resources in the US, UK and Italy 2.) Simulations 3.) Requirements

20-May-2016J. Reichenbacher (SDSM&T)3 DUNE Screening Resources at SDSMT -Large volume alpha/beta-radiation surface screener (fits large objects of any shape) -BEGe detector for gamma-spectroscopy -ICP-MS (Agilent 7900 with ~ppb sensitivity) -He-3 counters for neutron measurements

20-May-2016J. Reichenbacher (SDSM&T)4 DUNE Screening Resources at PNNL -ICP-MS (~ppt sensitivity) -laser ablation -SIMS -gamma assay screening -Have a wide variety of analytical tools available Eric Hoppe and John Orrell

20-May-2016J. Reichenbacher (SDSM&T)5 sample:NORPLEX, Micarta, NP 315, phenolic laminate with graphite, black weight:23.0 g live time: s detector:GePaolo radionuclide concentrations: Th-232: Ra-228:( ) Bq/kg ( ) E-6 g/g Th-228( ) Bq/kg ( ) E-6 g/g U-238: Ra-226( ) Bq/kg ( ) E-7 g/g Pa-234m(6 +- 3) Bq/kg (5 +- 2) E-7 g/g U-235 < 4.2 E-7 g/g K-40:( ) Bq/kg ( ) E-4 g/g Cs-137< 50 mBq/kg upper limits with k=1.645, uncertainties are given with k=1 (approx. 68% CL); Ra-228 from Ac-228; Th-228 from Pb-212 & Bi-212 & Tl-208; Ra-226 from Pb-214 & Bi-214; U-235 from U-235 & Ra-226/Pb-214/Bi-214 ======================================================================== sample:Current Inc., C770 ESD (Electro-Static Dissipative material), G10/FR4 (glass/epoxy) weight:89.0 g live time: s detector:GePaolo radionuclide concentrations: Th-232: Ra-228:( ) mBq/kg ( ) E-8 g/g Th-228( ) mBq/kg ( ) E-8 g/g U-238: Ra-226( ) mBq/kg ( ) E-9 g/g Pa-234m < 4.2 E-8 g/g U-235 < 1.2 E-8 g/g K-40:( ) Bq/kg ( ) E-4 g/g Cs-137< 3.7 mBq/kg upper limits with k=1.645, uncertainties are given with k=1 (approx. 68% CL); Ra-228 from Ac-228; Th-228 from Pb-212 & Bi-212 & Tl-208; Ra-226 from Pb-214 & Bi-214; U-235 from U-235 & Ra-226/Pb-214/Bi-214 ======================================================================== -> Existing Micarta and G10/FR4 screening results with low-background Ge-detector at Gran Sasso (Claudio Montanari) DUNE Screening Resources in Italy

Boulby Underground Germanium Suite (BUGS) Four detectors in ISO Class 6 clean room in new Boulby Laboratory Range of detector types o BEGe for low-energy sensitivity o P-type for high efficiency o Well-type for very small samples o Pre-screener for high activity materials Custom software for sample receipt, tracking, analysis, and assay report generation Managed through Boulby and DMUK (UCL/Oxford) Operations Automated LN2 fills Remote control, env. monitoring Emergency systems, UPS Interchangeable Pb+Cu castles Interlocking retractable roof to minimise systematics N2 purge fed through Pb/Cu to cavity 6 Slides from Chamkaur Ghag (UK Liaison)

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DetectorCrystal [U] mBq/kg [Th] mBq/kg Status ChalonerBEGe0.60.2Online LumpseyWell0.40.3Online LuneheadP-type0.70.2Online WiltonBEGe74Online 1.5 kg ULB SAGe 28 mm X 40 mm well ULB BE kg pre-screener 0.8 kg ULB BE keV threshold 2 kg ULB Ortec GEM-XX-95 8

ICP-MS UCL group has developed an in-house system dedicated to low background assays for rapid and direct U & Th assays –Agilent 7900 ICP-MS + HF capability with parts-per-trillion (ppt) sensitivity –All equipment in ISO Class 6 cleanroom (with fume cupboard and ISO class 4/5 laminar flow unit) –Microwave digestion and ashing ovens for clean and contained sample preparations –Acid purification and water systems 9

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20-May-2016J. Reichenbacher (SDSM&T)11 Neil Spooner Andrew Scarff

20-May-2016J. Reichenbacher (SDSM&T)12 Interface of Radiological Generator for LArSoft dune4apa_radiogen: { module_type: "RadioGen" Nuclide: [ "39Ar" ] # list of nuclides to simulate, supported so far: 39Ar, 60Co, 85Kr, 40K, 232Th, 238U BqPercc: [ ] # activity -- Becquerels per cc assumes 1.01 Bq/kg (typical for 39Ar) and a density of g/cc for LAr X0: [ ] # in cm in world coordinates, bottom corner of box X1: [ 475. ] # in cm in world coordinates, top corner of box Y0: [ ] # in cm in world coordinates, bottom corner of box Y1: [ 800. ] # in cm in world coordinates, top corner of box Z0: [ -55. ] # in cm in world coordinates, bottom corner of box Z1: [ 555. ] # in cm in world coordinates, top corner of box T0: [ ] # starting time in ns T1: [ ] # ending time in ns } (used by Gleb Sinev and Jason Stock, as well as Vic Gehman) (thanks to Tom Junk and Alex Himmel) -> missing Rn-222

20-May-2016J. Reichenbacher (SDSM&T)13 Ar-39 Input Compared to Spectrum with F(Z,E) + Shape Corr. Forbidden transition! RadioGen w/o F(E,Z) and w/o shape corr. stat. only w/ F(E,Z) + shape corr. w/ F(E,Z) w/ F(E,-Z) stat. only => due to forbiddenness more events near endpoint energy that are more likely to make a signal My shape corr. is based on Greg Kiefer’s & Andreas Piepke’s (Alabama)

20-May-2016J. Reichenbacher (SDSM&T)14 2.) External Generator in LArSoft (hepevt text-file as input) Usage: prodtext_dune35t.fcl … process_name: TextGen … physics.producers.generator.InputFileName : "K40Cath.txt" Advantages: -Can easily implement and play with different input spectra (done at SDSMT for Ar-39, Rn-222) -Can access MC_truth with handle (easier than with backTracker) -No bloated files with many hitless events -Easier geometry implementation for detector components such as field cage

20-May-2016J. Reichenbacher (SDSM&T)15 Results of Radioassay of Candidate Cathode/Field-Cage Materials sample:NORPLEX, Micarta, NP 315, phenolic laminate with graphite, black weight:23.0 g live time: s detector:GePaolo radionuclide concentrations: Th-232: Ra-228:( ) Bq/kg ( ) E-6 g/g Th-228( ) Bq/kg ( ) E-6 g/g U-238: Ra-226( ) Bq/kg ( ) E-7 g/g Pa-234m(6 +- 3) Bq/kg (5 +- 2) E-7 g/g U-235 < 4.2 E-7 g/g K-40:( ) Bq/kg ( ) E-4 g/g Cs-137< 50 mBq/kg upper limits with k=1.645, uncertainties are given with k=1 (approx. 68% CL); Ra-228 from Ac-228; Th-228 from Pb-212 & Bi-212 & Tl-208; Ra-226 from Pb-214 & Bi-214; U-235 from U-235 & Ra-226/Pb-214/Bi-214 ======================================================================== sample:Current Inc., C770 ESD (Electro-Static Dissipative material), G10/FR4 (glass/epoxy) weight:89.0 g live time: s detector:GePaolo radionuclide concentrations: Th-232: Ra-228:( ) mBq/kg ( ) E-8 g/g Th-228( ) mBq/kg ( ) E-8 g/g U-238: Ra-226( ) mBq/kg ( ) E-9 g/g Pa-234m < 4.2 E-8 g/g U-235 < 1.2 E-8 g/g K-40:( ) Bq/kg ( ) E-4 g/g Cs-137< 3.7 mBq/kg upper limits with k=1.645, uncertainties are given with k=1 (approx. 68% CL); Ra-228 from Ac-228; Th-228 from Pb-212 & Bi-212 & Tl-208; Ra-226 from Pb-214 & Bi-214; U-235 from U-235 & Ra-226/Pb-214/Bi-214 ======================================================================== Results with Ge-detector at Gran Sasso (Claudio Montanari )

20-May-2016J. Reichenbacher (SDSM&T)16 K-40 External Generator in LArSoft (hepevt text-file as input) pulse height vs x photo electrons vs x simulated K-40 events on field cage by Jason Stock (SDSMT)

20-May-2016J. Reichenbacher (SDSM&T)17 Gleb Sinev -> Rn-222 ~ Ar-39

20-May-2016J. Reichenbacher (SDSM&T)18

20-May-2016J. Reichenbacher (SDSM&T)19 DUNE Radiopurity&Purity Requirements for FD/protoDUNE Electron lifetime in liquid argon (subsequent requirements on O 2, N 2 & H 2 0 levels): >3.0 ms (could become larger) -> Requirements on Radiopurity driven by intrinsic Ar-39 level (1 Bq / kg) Radon emanation requirement (e.g. G10 material for cathode): <75 mHz / m^2 (prelim.) Requirement for radioactive plate-out on surfaces (e.g. from radon daughters): <200 mBq / m^2 (prelim.) Requirement on radon content in liquid argon: <10 mBq / kg (factor 14 less than in 1 l air, factor 1000 more than XENON1t and 10000x more than LZ goal) -> commercial RAD7 counter will do to see 18 mBq / m^3 ? -> control filters with ICP-MS?

20-May-2016J. Reichenbacher (SDSM&T)20 DUNE Cleanliness Requirements for FD/protoDUNE -ISO 7 or 8 might be sufficient (-> check with samples from 35 t prototype) -Dust/dirt can trigger HV break down? -> Take tape-lifts and/or high resolution photographs of interior of 35 t prototype before its decommissioning in mid June