1 / 26

Muon Capture on the Deuteron Motivation for a new Experiment B e r n h a r d L a u s s

Muon Capture on the Deuteron Motivation for a new Experiment B e r n h a r d L a u s s U C B e r k e l e y for the MuCAP Collaboration Petersburg Nuclear Physics Institute Paul Scherrer Institut University of California - Berkeley and LBNL

kenton
Download Presentation

Muon Capture on the Deuteron Motivation for a new Experiment B e r n h a r d L a u s s

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Muon Capture on the Deuteron Motivation for a new Experiment B e r n h a r d L a u s s U C B e r k e l e y for the MuCAP Collaboration Petersburg Nuclear Physics Institute Paul Scherrer Institut University of California - Berkeley and LBNL University of Illinois - Urbana Champaign Universite Catholique de Louvain Boston University University of Kentucky - Lexington Universität München The muD-Project - experiment under consideration - encourage strongly community input APS April 2004 - Denver

  2. m 2 hyperfine states: (1/2) md  (3/2) md  doublet capture rate: Ld 1/2 ~ 400s-1 quartet capture rate: Ld 3/2 ~ 10s-1 md md n n d F=1/2 F=3/2 LD W LQ m- nm n n nm The Basic Process to be investigated is muon capture on the deuterium doublet state m + d  n + n + n APS April 2004 - Denver

  3. Why a new experiment on md-capture ? • First precise Measurement of charge current • reaction in a 2 Nucleon system • Test of 2-body currents • (Axial) Meson Exchange Currents • Resolve unclear experimental situation • Determine L1,A • -> relevant for Neutrino experiments & • Solar Model APS April 2004 - Denver

  4. The Present Experimental Situation is unsatisfying lifetime measurement F= 5%; ultraclean D2 gas n-measurement F=4% gas, T=40K 409±40 lifetime measurement liquid D2, T=18K 470±29 n-measurement H2-D2(5%) gas mixture, T=293K but only if pure 1/2 population assumed / statistical mix -> x3 n-measurement liquid H2-D2(0.32%) mixture T=18K Problems: n-method: depends on n-efficiency and energy threshold -> needs theory for extraction of L. lifetime method: needs high statistics & target purity. APS April 2004 - Denver

  5. New Calculation Ando et al. PLB 533 (2002) EFT* (HBCPT+EFT) reduces MECs effect |1B|2 = 370 s-1 |1+2B|2 = 386 s-1 Test of the Standard Nuclear Physics Approach and of Meson Exchange Currents SNPA 2-body nuclear system is well known  test of our description of nuclear response to weak probes at intermediate energies; two nucleon interaction.  test of MECs (p,r exchange / significant D-isobar current) MECs are sensitive to short range effects enhanced for high energetic neutrons  ann- final state interaction  gp dependence (similar to mp-capture) SNPA Tatara et al PRC42(1990) MECs 10% of total rate APS April 2004 - Denver

  6. Theory The Present Experimental Situation is controvers lifetime measurement F= 5%; ultraclean D2 gas n-measurement F=4% gas, T=40K 409±40 lifetime measurement liquid D2, T=18K 470±29 Theory cannot account for rates at 470 s-1 ! ! ! n-measurement H2-D2(5%) gas mixture, T=293K but only if pure 1/2 population assumed / statistical mix -> x3 n-measurement liquid H2-D2(0.32%) mixture T=18K Problems: n-method: depends on n-efficiency and energy threshold -> needs theory for extraction of L. lifetime method: needs high statistics & target purity. APS April 2004 - Denver

  7. EFT(p) EFT* - uses a low-energy expansion scheme with a set cut-off parameter for regularization - provides independent framework with model-independent results when all low-energy coefficients in the effective Lagrangian are known a NLO calculation contains one not so well determined parameter denoted L1,A or dR - Ld can be used to determine precisely the low-energy parameter within a 2-body system (Ando-Park-Kubodera-Myhrer PLB533(2002)25 / Kammel-nucl-ex/0304019 ) ^ APS April 2004 - Denver Test of calculational approach via Effective Field Theory

  8. Astrophysical Interest because of the close connection between muon capture and neutrino scattering calculation EFT: Class of axial current reactions related by one single low-energy parameter L1,A (Butler-Chen-Kong PRC63 (2001)035501) - pp-fusion - tritium b-decay - n d &n d scattering & breakup reactions -> SNO L1,A can be determined from: _ 3-body current ? assumes standard 8B shape no solar model uncertainties included (fB,12 ,dm212constraint) _ suggested md capture ? ± 1.5 fm3 Chen-Kammel  would be the most precise determination from 2-body system APS April 2004 - Denver

  9. Knowledge of L1,A is important for a precision determination of neutrino parameters The leading two-body current parametrized by L1,A is the dominant uncertainty of every low-energy weak interaction deuteron breakup process including SNO’s CC and NC reactions ! (Chen-Heeger-Robertson PRC67-2003 ) We emphasize the importance of fixing the axial counter term through a direct experimental measurement ! (Butler-Chen-Kong/PRC63-2001) L1,A necessary to determine absolute rates in SNO ! constrain 13 ! APS April 2004 - Denver

  10. Due to the complexity of muonic processes in deuterium it is very important for a precision measurement to determine the most favourable experimental conditions. APS April 2004 - Denver

  11. recycling m mCF Lhf md md dmd F=1/2 F=3/2 LD LQ n n n m3He hf population monitoring nm capture background ! Muons are subject to a Complex Chain of Processes in Deuterium APS April 2004 - Denver

  12. F = 0.01 LHD T = 300K F = 0.1 LHD T = 300K Well known Variation of the Muonic Deuterium Hyperfine Populations with Temperature and Density — 1/2 states— 3/2 states— sum 1/2+3/2 — dd-fusion neutron APS April 2004 - Denver

  13. F = 0.01 LHD T = 80K F = 0.1 LHD T = 80K Well known Variation of the Muonic Deuterium Hyperfine Populations with Temperature and Density liquid N2 - cooling possible !!! — 1/2 states— 3/2 states— sum 1/2+3/2 — dd-fusion neutron APS April 2004 - Denver

  14. MuCAP  Experience with precision Lifetime Measurement in Hydrogen Comparison Hydrogen / Deuterium Experiments in D2 easier - isotopic purity requirements less stringent in D2 harder - muonic molecular processes - additional neutron measurement - control of hyperfine states - cooled TPC detector with higher density (smaller chamber) APS April 2004 - Denver

  15. Setup Stage 1 - Lifetime Measurement ( MuCAP ) X X e-detectors  mu-detectors  cooled TPC  D2 gas system  measure at 300 K to  3% precision with present setup APS April 2004 - Denver

  16. EFT* little contribution to L because of small overlap of wavefunctions of the deuteron and the 2 neutrons n pEFT pEFT ?  n final state interaction nn-scattering length Investigation of Energy Dependence - Dalitz Plot m + d  n + n + n APS April 2004 - Denver

  17. deuterium gas cooled with liquid N2 with enough physics motivation Setup Stage 2 -Neutron TOF APS April 2004 - Denver

  18. Thanks for your attention ! APS April 2004 - Denver

  19. APS April 2004 - Denver

  20. APS April 2004 - Denver

  21. m md md F=1/2 F=3/2 LD LQ n n nm APS April 2004 - Denver

  22. recycling m mCF Lhf md md dmd F=1/2 F=3/2 LD LQ n n n m3He hf population monitoring nm capture background ! APS April 2004 - Denver

  23. m Lhf md md F=1/2 F=3/2 LD LQ n n nm APS April 2004 - Denver

  24. dmd APS April 2004 - Denver

  25. recycling mCF n m3He hf population monitoring capture background ! APS April 2004 - Denver

  26. recycling mCF dmd n m3He hf population monitoring capture background ! APS April 2004 - Denver

More Related