A Review of the Ge collaboration between USC

A Review of the Ge collaboration between USC and PNNL Harry Miley Pacific Northwest National Laboratory

Outline • Pre-history: before we were fab • The race for 2 nu DBD T 1/2: materials, depth, materials, mass, materials, isotopes… • The TWINS • Sov. Det. Ops • Enriched material: IGEX • All things shiny and distracting • Conclusions

Before we were fab (i) • Hanford Works environmental surveillance • Early high-sensitivity radiation detection using Na. I underground • Methodical bkg reduction & sensitivity increase for environmental samples

Before we were fab (ii) Pure science apps • The atmosphere • The oceans • Cross sections • Meteorites • Lunar studies • Astronaut studies

Collaboration Starting Point • Approach: Fiorini’s Internal Source Method in 76 Ge • Plan: Rebuild existing low background germanium detector – THEN: make a multicrystal cryostat for a large mass experiment – MAYBE: Get enriched isotopes one day

The Race for 2 n DBD T½ • • Diode-M Good materials, Arkie shield 1983: Homestake Pb, Fe, Cu shield Old Pb bricks = 1 Ph. D Indium contact replaced with Pb Single bead of solder: Po-210

The Road Not Taken • Superdetector – – M 02287, still on the books 14 crystals in 2 cryostats Collaboration with PGT After many minor issues, passed all tests – Never populated with crystals, but… – Early thermal validation of our Majorana Ref Design

Detour: The Majoron • The bump that wasn’t • Alpha background linear from 5 Me. V to 2615 ke. V • We just needed bkg to be linear for one more Me. V. • Guess what. It wasn’t. “High Energy guys need an accelerator to create particles. You only need a computer. ” -- Krish Gounder “Some you win, some you lose, some get rained out. ” – Frank Avignone

TWINS: A scientist’s dream • Casual conversation in 1986: – 68 Ge/60 Co limits sensitivity – Could you rapidly deep mine Ge and make detectors? – Yes, if you buy all the sugar in St. George UT & Quapaw, OK • Result: Best low bkg detectors yet built – Two 1. 05 kg Ge xtals – Elow << 10 ke. V – Measured: ~ 8 atoms per cc 68 Ge (somewhat suppressed) – Also <9 m. Bq/kg 232 Th in Cu Shielding: 450 yo Pb 2000 yo Pb Eformed Cu

Some Comparisons

Finally, some pay dirt! • TWINS operated remotely at >50% duty cycle for two years. – Thompson – Aalseth • Simplistic T 1/2 – Minimal manipulation – Internal ‘debate’ > 1 yr PRL 65 No 25 (1990) Miley et al How can you be sure this is double-beta decay and not yet another background?

Sov. Det. Ops • Challenge: – Move a Ge. Li from Baksan to Homestake – Repackage in a TWIN cryostat • Don’t kill it • Don’t shut Homestake – Achieve PNNL-USC background levels on the first shot • Result: Confirmation of observation of two neutrino double-beta decay PLB 256 No. 3, 4 (1991) Avignone et al Only thing in common is count rate divided by number of 76 atoms! T 1/2 in agreement with natural

Enriched 76 Ge: An Addiction • As many know, • What few know is how enriching from 7% to addictive it is 86% gives a large kick – White powder in sensitivity with no – ~$50/gram increase in BKG • Need a Russian enrichment facility! • Need an international collaboration!

Centrifugation in Russia Frank Avignone Glasnost and Perestroika strike…. www. cia. gov May, 1970 • Electrochemical Combine Plant (ECP of Zelenogorsk) has supplied all the IGEX and HM 76 Ge Formerly known as K-45, also known as Svetlana Plant Large facility that provides ~30% of Russia’s LEU Features department of Superhttp: //www. nti. org/db/nisprofs/russia/fissmat/enrichme/ekhz. htm Clean Materials http: //www. ecp. ru/en/index. shtml

IGEX: International Germanium EXperiment • Location: Spain, Canfranc tunnel • Assembly: Tennelec plus our best materials – Rico Grande 1, 2, 3 • Background lessons • Spanish lessons • German lessons

All things shiny and distracting • Axions at ORNL – Plus the Princeton gang (Calaprice to Kouzes) • Electron decay • Early WIMP limits – Spergel, Drukier • Dark Matter: Cosme – U Zaragoza: Angel and Julio Morales et al • 2 n DBD of 100 Mo – ITEP: Barabash et al • Axions at Sierra Grande… – Konstantin Zioutas, Rick Creswick, Smuel Nussinov , TANDAR, et al – Which became CAST

1998 changed everything • Super-K result: Neutrinos have mass! • New era of low level measurements required

New Era of ULB Materials and Mechanical Engineering • New approach: 1. Find applications 2. Get ACTUAL funding 3. Hire experts • Share funds with nonphysicists like chemists, engineers, etc

Where are we, and which way are we pointing? • Our group has grown – 35 -> 120 – WAS: Nuclear Chemistry – IS: Radiation Detection and Nuclear Science – HAD: 1 rad chemist (78) – HAS: 5 rad chemists <29> – JLAB, Fermi. Lab physicsts – As many of Frank’s students as possible • And we are getting our own shallow underground lab – Brodzinski Underground Lab • Our interests are broad – Remote detection D • Improved portals DB o • Automated systems trin u • Flight systems Ne ter t ero – Non-proliferationering R&D Ma Z rk t Da – Explosion monitoring cat ns • Global networks ent her interrogation –Co Active – – Separations chemistry US Domestic responses New fuel cycles Mass spec (many)

Summary • A 28 year collaboration – Mostly Frank and Ron • Reduced backgrounds by more than a millionfold • Started new efforts at PNNL – Roll-your-own cryostat – Electroplating – Pulse processing • Launched several (formerly) young people – Miley, Guerard, Collar, Aalseth, Hossbach, others – Smart, Thompson, etc • Drove theorists crazy making revised double-beta decay T 1/2 calculations • Outlasted many other Ge DBD groups (not HM, tho) • Established 329 building as “don’t show to DOE” zone • Only ~$1 M in DOE/HEP funds + ? ? NSF with only 2 n DBD and tight limits on 0 n DBD to show for it • Established a chance for US leadership in a world 1 ton 76 Ge experiment

Questions? Only known picture of them working. BTW, that’s Frank. They forgot the reflector underneath.