Studies of Muon-Induced Radioactivity at NuMI Radioactivity at NuMI - PowerPoint PPT Presentation

Studies of Muon-Induced Radioactivity at NuMI Radioactivity at NuMI David Boehnlein Fermi National Accelerator Laboratory (on behalf of the JASMIN Collaboration) NuFact09 – July 24, 2009 NuFact09 July 24, 2009

The JASMIN Collaboration • D. J. Boehnlein, A. F. Leveling, N. V. Mokhov*, K. Vaziri • Fermi National Accelerator Laboratory • Y. Iwamoto, Y. Kasugai, N. Matsuda, H. Nakashima*, Y. Sakamoto* • Japan Atomic Energy Agency • M. Hagiwara, Hiroshi Iwase, N. Kinoshita, H. Matsumura, T. Sanami, A. Toyoda • High Energy Accelerator Research Organization (KEK) • • H Yashima H. Yashima • Kyoto University Research Reactor Institute • H. Arakawa, N. Shigyo • Kyushu University • H. S. Lee • Pohang Accelerator Laboratory • K. Oishi • Shimizu Corporation p • T. Nakamura • Tohoku University • Noriaki Nakao • A Aurora, Illinois Illi i * Co-Spokesperson July 24, 2009 NuFact09 - David Boehnlein NuFact09 - David Boehnlein 2 2

The JASMIN Experiment • JASMIN – Japanese & American Study of Muon Interactions and Neutron Detection Muon Interactions and Neutron Detection (Fermilab T972) • A study of shielding and radiation physics effects at high-energy accelerators • Studies to date have focused on the anti- proton production target (AP0) and NuMI. p oto p oduct o ta get ( 0) a d u • We present here status of work in progress to study activation at the NuMI progress to study activation at the NuMI muon alcoves. July 24, 2009 NuFact09 - David Boehnlein NuFact09 - David Boehnlein 3 3

Experimental Goals of JASMIN • Benchmarking of Monte Carlo codes • Radiation safety • Study of muon interactions St d f i t ti • Material activation • Shielding • Muon detection & measurement • Improved characterization of NuMI • Improved characterization of NuMI muon monitors. July 24, 2009 July 24, 2009 NuFact09 - David Boehnlein NuFact09 - David Boehnlein 4 4

Motivation • Why is a neutrino experimenter talking to a group of accelerator physicists about a group of accelerator physicists about radiation physics? • This workshop is considering machines that could produce unprecedented muon intensities. • If such machines are to be built, one must suc ac es a e to be bu t, o e ust consider the radiological issues, including the potential for radioactivation c ud g t e pote t a o ad oact at o due to muons. • Monte Carlo codes used for simulations • Monte Carlo codes used for simulations should accurately account for it. July 24, 2009 NuFact09 - David Boehnlein NuFact09 - David Boehnlein 5 5

Source of electron, photon and neutron Photo nuclear reaction A n  e -  A e + Bremsstrahlung Electro-magnetic cascade Bremsstrahlung Pair production Pair production Radiations around intense muon beam (T Sanami) Radiations around intense muon beam (T.Sanami) July 24, 2009 NuFact09 - David Boehnlein 6

Neutrinos at the Main Injector • The NuMI beamline focuses a ν μ beam toward Soudan, Minnesota. Soudan, Minnesota. • Since the neutrinos come from 2-body pion decay, the world’s most intense neutrino beam is also the world’s most intense muon beam. l th ld’ t i t b • Arrays of ionization chambers in downstream alcoves monitor muons co-produced with the alcoves monitor muons co produced with the neutrinos. July 24, 2009 July 24, 2009 NuFact09 - David Boehnlein NuFact09 - David Boehnlein 7 7

NuMI Muon Monitoring Alcoves Decay pipe muons muons Abs orber Alcove-0 Alcove-1 Alcove-2 Alcove-3 Alcove-4 0 m 13.7 m 33.5 m 67.1 m • Schematic layout of the muon alcoves at S f NuMI • Note that Alcove 1 is in the Absorber Hall. • See L. Loiacono’s talk at this workshop See L. Loiacono s talk at this workshop for a discussion of the muon monitors. July 24, 2009 July 24, 2009 NuFact09 - David Boehnlein NuFact09 - David Boehnlein 8 8

Estimated Muon Fields Alcove Charged Particle Beam Size Fluence Fluence 1 6.5 x 10 5 cm -2 10 -12 ppp 190 cm 2 0.9 x 10 5 cm -2 10 -12 ppp 250 cm 3 0.35 x 10 5 cm -2 10 - 190 cm 12 ppp • Predicted data from Kopp et al. [NIM A 568 (2006)503] • • Assumes Low Energy Beam Assumes Low-Energy Beam. • Beam size is FWHM. • Neutrons < 1% in downstream alcoves. Neutrons < 1% in downstream alcoves. July 24, 2009 July 24, 2009 NuFact09 - David Boehnlein NuFact09 - David Boehnlein 9 9

Procedure I • Copper and Aluminum disks were placed in alcoves 1 -4. • Disks are 8 cm Disks are 8 cm diameter x 1 cm thick. • Beam exposure was Beam exposure was 22.8 hours. • NuMI beam put 6 26 x NuMI beam put 6.26 x 10 17 p.o.t. • Additional samples Additional samples were placed to measure neutron activation. July 24, 2009 July 24, 2009 NuFact09 - David Boehnlein NuFact09 - David Boehnlein 10 10

Procedure II • JASMIN operates parasitically with NuMI NuMI. • Samples are placed and retrieved Samples are placed and retrieved during natural beam-down periods. • Isotopic signatures are measured on High-Purity Ge counters at High- g y g Intensity Lab. • Operations so far have occured in O i f h d i November 2007 and November 2008. July 24, 2009 July 24, 2009 NuFact09 - David Boehnlein NuFact09 - David Boehnlein 11 11

Radionuclides observed in Samples Samples • This table summarizes the summarizes the radionclides observed in the exposed copper samples. • 54 Mn, 57 Co, 60 Co have substantial half-lives (beyond a reasonable cool- d down period for i d f accelerator maintenance) maintenance). July 24, 2009 NuFact09 - David Boehnlein 12

Preliminary Results • Attenuation of muons, as shown by yield y y ratios normalized to Alcove 2. • Yield ratios vs. distance (top) • Yield ratios vs. nucleons emitted from target nucleus (bottom) • Note Aluminum results are included ( 24 N ) ( 24 Na). • Figures courtesy of H. July 24, 2009 July 24, 2009 NuFact09 - David Boehnlein NuFact09 - David Boehnlein 13 13 M t

Preliminary Results II • Activation Products 10 -32 Alcove-1 oton -1 ) on copper samples by pp p y 10 -33 yields (atom -1 pro mass number. 10 -34 • Alcove 1 shows Alcove 1 shows 10 -35 Mass y evidence of neutron 10 -36 activation. 10 -37 20 30 40 50 60 Product mass number Product mass number • The narrow line is a fit 10 -33 to an empirical Alcove-2 -1 ) Experimental 10 -34 10 34 MARS15 MARS15 formula for ds (atom -1 proton photospallation 10 -35 (Rudstam et al Phys (Rudstam et al. Phys 10 -36 10 Mass yield Rev 126, 5 (1962) 10 -37 1852). 1852). 10 -38 10 35 40 45 50 55 60 65 Product mass number • The lower plot July 24, 2009 July 24, 2009 NuFact09 - David Boehnlein NuFact09 - David Boehnlein 14 14 histogram is a

Summary • JASMIN has measured radionuclides produced in Aluminum and copper produced in Aluminum and copper in the muon alcoves • It’s not clear how much of the activity is produced by muons and how much by muon-produced neutrons (for radiation safety, does it ( y matter?) • MARS15 simulations give good • MARS15 simulations give good predictions of dose rates and activation activation. • Studies will continue in Fall 2009. July 24, 2009 July 24, 2009 NuFact09 - David Boehnlein NuFact09 - David Boehnlein 15 15

Backup Slides . . . July 24, 2009 NuFact09 - David Boehnlein 16

ACNET Readout for Exposure July 24, 2009 July 24, 2009 NuFact09 - David Boehnlein NuFact09 - David Boehnlein 17 17

10 -6 Alcove-1 10 -7 Alcove-2 Alcove-3 m -2 proton -1 ) ) Alcove 4 Alcove-4 10 -8 10 -9 x (GeV -1 cm 10 -10 x 10 -8 proton -1 ) 8 10 -11 Muon flux n flux (GeV -1 cm -2 p 6 6 10 -12 4 10 -13 2 Muon 10 -14 0 0 2 4 6 8 10 Energy (GeV) 10 -15 10 -1 10 0 10 1 10 2 Energy (GeV) Energy (GeV) FIG. Calculated muon spectra in units of number of muons per GeV, per cm 2 , and per primary proton in Alcove 1 Alcove 2 Alcove 3 and proton in Alcove-1, Alcove-2, Alcove-3, and Alcove-4. July 24, 2009 NuFact09 - David Boehnlein 18

Samples for Neutron Studies AA 06 AA-06 AA-07 AA-08 AA-09 m 100 cm Distance AA-10 AA-11 each 10 cm AA-12 AA-13 AA-13 60 cm AA-14 AA-15 AA-16 AA 17 AA-17 Beam Size: 3 ft. diameter 3 ft di t Decay Pipe: Decay Pipe: 6 ft. diameter July 24, 2009 NuFact09 - David Boehnlein 19

Activation Yields vs Charge • Alcove 1 10 1 0711NuMI Alcove-1 Na 24 Na-24 • Plot of nat Cu nuclides 10 0 lds vs change C C- C+ C+ sobaric yiel △ ▽ in nuclear charge. 10 1 10 -1 raction of is • Fitted to tted to Fr Rudstam’ 10 -2 s s I empirical □ 10 -3 formula. 5 4 3 2 1 0 -1 -2 -3 -4 -5 Neutron deficient Neutron deficient Neutron rich Neutron rich Z-Z p Z-Z July 24, 2009 NuFact09 - David Boehnlein 20

Theoretical calculation Theoretical calculation Target (Graphite) 120 GeV -256kW typical Decay pipe (670m long – 2m diam.) MARS code MARS code Simulate interaction and transport of 120 GeV proton and secondary particles Fermilab rock Ca : O : C : Mg : H = 0 09 : 0 56 : 0 17 : 0.09 : 0.56 : 0.17 : 0.08 : 0.10 ρ =2.85 g/cm 3 Absorber hall and muon alcoves Radiations around intense muon beam (T.Sanami) July 24, 2009 NuFact09 - David Boehnlein 21