EXPLORATORY STUDIES OF ANOMALOUSLY LONG-LIVED HADRONIC ATOMS

• Project/Area Number: 04101002
• Research Category: Grant-in-Aid for Specially Promoted Research
• Allocation Type: Single-year Grants
• Research Institution: INSTITUTE FOR NUCLEAR STUDY,UNIVERSITY OF TOKYO
• Principal Investigator: YAMAZAKI Toshimitsu INSTITUTE FOR NUCLEAR STUDY,UNIVERSITY OF TOKYO,PROFESSOR EMERITUS, 原子核研究所, 名誉教授 (80011500)
• Co-Investigator(Kenkyū-buntansha): ITO Yasuo RESEARCH CENTER FOR NUCLEAR SCIENCE & TECH,UNIVERSITY OF TOKYO,ASSOC.PROF., 原子力研究総合研究センター, 助教授 (40011150) ; MORITA Norio INSTITUTE FOR MOLECULAR SCIENCE,UNIVERSITY OF TOKYO ASSOC.PROF., 分子科学研究所, 助教授 (30134654) ; HAYANO Ryugo FACULTY OF SCIENCE,UNIVERSITY OF TOKYO,PROF., 大学院・理学系研究科, 教授 (30126148)
• Project Period (FY): 1992 – 1996
• Project Status: Completed (Fiscal Year 1996)
• Budget Amount: ¥286,000,000 (Direct Cost: ¥286,000,000); Fiscal Year 1996: ¥5,000,000 (Direct Cost: ¥5,000,000); Fiscal Year 1995: ¥20,000,000 (Direct Cost: ¥20,000,000); Fiscal Year 1994: ¥75,000,000 (Direct Cost: ¥75,000,000); Fiscal Year 1993: ¥81,000,000 (Direct Cost: ¥81,000,000); Fiscal Year 1992: ¥105,000,000 (Direct Cost: ¥105,000,000)
• Keywords: ANTIPROTONS / LASER SPECTROSCOPY / HELIUM ATOM / PIONS / NUCLEUS / 反物質 / レーザー分光 / CERN / LEAR / π中間子原子 / ハドロン原子 / 準安定反陽子ヘリウム原子 / レーザー共鳴転移 / 反陽子消滅 / 反陽子原子

Research Abstract

(1) Extensitive experimental programs on long-lived antiprotons in helium media have been carried out by using the antiproton beam from LEAR at CERN.First, delayd annihilation time spectra of antiprotons were measured precisely. Not only in liquid phase but also in gas and solid phase 3% of stopped antiprotons were observed to have lifetimes about 3-4 microseconds. Secondly, laser resonance spectroscopy was developed to clarify the mechanism of this anomalous longevity. The method proposed was to induce stimulated transitions between a metastable state and a short-lived state using an intense pulsed laser and to detect the transition as a sharp spike in delayd annihilation time spectra. Successful observations of many resonance transitions came out. The resonance wavelengths observed agree with theoretical expectations, which established that the metastability arises from long-lived states of large angular momenta. The precise spectroscopy including the observation of hyperfine structure has provided important data on the particle-antiparticle symmetry and few-body theories. Various effects of surrounding helium and foregn atoms and molecules on the metastable atoms have also been found and studied by laser spectroscopy.
(2) Deeply-bound pionic states in 207Pb have been discocovered at GSI using the 208Pb (d, 3He) reaction at 600 MeV.

Research Products

• [Publications] T. Yamazaki et al.,: "Formattion of long-lived gas-phase antiprotonic helium atoms" Nature. 361. 238-240 (1993)
  • Description: 「研究成果報告書概要(和文)」より
• [Publications] E. Widmann et al.: "Phase snd density dependence of the delayed annihilation of metastable antipronic helium atoms in gas, liquid and solid helium" Phys. Rev.A51. 2870-2880 (1995)
  • Description: 「研究成果報告書概要(和文)」より
• [Publications] E. Widmann et al.: "Effects of impurity atoms and molecules on the lifetime of antiprotonic heliunm atoms" Phys. Rev.A53. 3129-2117 (1996)
  • Description: 「研究成果報告書概要(和文)」より
• [Publications] B. Ketzer et al.: "Isotope effects on delayed annihilation time spectra of antiptotonic helium atoms in a low-temperature gas" Phys. Rev.A53. 2108-2117 (1996)
  • Description: 「研究成果報告書概要(和文)」より
• [Publications] N.Morita et al.,: "First observation of laser-induced resonant annihilation in metastable antiprotonic helium atoms" Phys. Rev. Lett.72. 1180-1183 (1994)
  • Description: 「研究成果報告書概要(和文)」より
• [Publications] R. S. Hayano et al.,: "Laser studies of the decay chain of metastable antiprotonic helium atoms" Phys, Rev. Lett.73. 1485-1488 (1994)
  • Description: 「研究成果報告書概要(和文)」より
• [Publications] F. Maas et al.: "Laser-induced resonance transition at 470.724nm in the v=n-1-1=2 cascade of metastable antiprotonic helium atoms" Phys. Rev.A52. 4266-4269 (1995)
  • Description: 「研究成果報告書概要(和文)」より
• [Publications] H. A. Torii et al.,: "Laser-induced resonant transitions in the v=n-1-1=2 and 3 metastable cascades of antiprotonic 3He atoms" Phys. Rev.A53. R1931-1934 (1996)
  • Description: 「研究成果報告書概要(和文)」より
• [Publications] A. Niestroj et al.: "Analog measurement of delayed antiproton annihilation time spectrea in a high intensity pulsed antiproton beam" Nucl. Instr. Meth.A373. 411-414 (1996)
  • Description: 「研究成果報告書概要(和文)」より
• [Publications] R. S. Hayano et al.,: "Observation of double resonant laser induced transitions in the v=n-1-1=2 metastable cascade of antiprotonic helium-4 atoms" Phys. Rev.A55. 1-4 (1997)
  • Description: 「研究成果報告書概要(和文)」より
• [Publications] T. Yamazaki et al.,: "Laser resonance studies of the interactions of metastable antiprotonic helium atomcules pbar-4He+ with surrounding H2 molecules″" Chem. Phys. Lett.265. 137-144 (1997)
  • Description: 「研究成果報告書概要(和文)」より
• [Publications] B. Ketzer et al.: "Observation of hydrogen-asseted laser-induced resonant transitions between metastable states of antiprotonic helium atoms″" Phys. Rev. Lett.78. 1671-1674 (1997)
  • Description: 「研究成果報告書概要(和文)」より
• [Publications] T. Yamazaki et al.: "Discovery of deeply bound pi-states in 208pb(d, 3He)reaction" Z. Phys.A355. 219-221 (1996)
  • Description: 「研究成果報告書概要(和文)」より
• [Publications] T. Yamazaki et al.: "High precision structural studies of the antiprotonic helium atom pbar 4He+ by observing laser resonances with Delta v=Delta(n-1-1)=2″" Phys. Rev. A,. (in press).
  • Description: 「研究成果報告書概要(和文)」より
• [Publications] E. Widmann et al.: "Observation of a hyperfine splitting in a Delta(n-1-1)=2 transition in metastable antiprotonic 4He atoms″" Phys. Lett. B,. (to be published).
  • Description: 「研究成果報告書概要(和文)」より
• [Publications] T.Yamazaki et al.: "Formation of long-lived gas-phase antiprotonic helium atoms and quenching by H2" Nature. 361. 238-240 (1993)
  • Description: 「研究成果報告書概要(欧文)」より
• [Publications] N.Morita et al.: "First observation of laser-induced resonant annihilation in metastable antiprotonic helium atoms" Phys.Rev.Lett.72. 1180-1183 (1994)
  • Description: 「研究成果報告書概要(欧文)」より
• [Publications] R.S.Hayano et al.: "Laser studies of the decay chain of metastable antiprotonic helium atoms" Phys.Rev.Lett.73. 1485-1488 (1994)
  • Description: 「研究成果報告書概要(欧文)」より
• [Publications] F.Maas et al.: "Laser-induced resonance transition at 470.724 nm in the v=n-1-1=2 cascade of metastable antiprotonic helium atoms" Phys.Rev.A52. 4266-4269 (1995)
  • Description: 「研究成果報告書概要(欧文)」より
• [Publications] E.Widmann et al.: "Phase and density dependence of the delayd annihilation of metastable antiprotonic helium atoms in gas, liquid and solid helium" Phys.Rev.A51. 2870-2880 (1995)
  • Description: 「研究成果報告書概要(欧文)」より
• [Publications] E.Widmann et al.: "Effects of impurity atoms and molecules on the lifetime of antiprotonic helium atoms" Phys.Rev.A53. 3129-3139 (1996)
  • Description: 「研究成果報告書概要(欧文)」より
• [Publications] B.Ketzer et al.: "Isotope effects on delayd annihilation time spectra of antiprotonic helium atoms in a low-temperature gas" Phys.Rev.A53. 2108-2117 (1996)
  • Description: 「研究成果報告書概要(欧文)」より
• [Publications] H.A.Torii et al.: "Laser-induced resonant transitions in the v=n-1-1=2 and 3 metastable cascades of antiprotonic 3He atoms" Phys.Rev.A53. R1931-1934 (1996)
  • Description: 「研究成果報告書概要(欧文)」より
• [Publications] A.Niestroj et al.: "Analog measurement of delayd antiproton annihilation time spectra in a high intensity pulsed antiproton beam" Nucl.Instr.Meth.A373. 411-414 (1996)
  • Description: 「研究成果報告書概要(欧文)」より
• [Publications] T.Yamazaki et al.: "Discovery of deeply bound pi-states in 208Pb (d, 3He) reaction" Z.Phys.A355. 219-221 (1996)
  • Description: 「研究成果報告書概要(欧文)」より
• [Publications] R.S.Hayano et al.: "Observation of double resonant laser induced transitions in the v=n-1-1=2 metastable cascade of antiprotonic helium-4 atoms" Phys.Rev.A55. 1-4 (1997)
  • Description: 「研究成果報告書概要(欧文)」より
• [Publications] T.Yamazaki et al.: "Laser resonance studies of the interactions of metastable antiprotonic helium atomcules pbar-4He+ with surrounding H2 molecules" Chem.Phys.Lett.265. 137-144 (1997)
  • Description: 「研究成果報告書概要(欧文)」より
• [Publications] B.Ketzer et al.: "Observation of hydrogen-assited laser-induced resonant transitions between metastable states of antiprotonic helium atoms" Phys.Rev.Lett.78. 1671-1674 (1997)
  • Description: 「研究成果報告書概要(欧文)」より
• [Publications] T.Yamazaki et al.: "High precision structural studies of the antiprotonic helium atom pbar 4He+ by observing laser resonances with Delta v=Delta (n-1-1) =2" Phys.Rev.A. (in press).
  • Description: 「研究成果報告書概要(欧文)」より
• [Publications] E.Widmann et al.: "Observation of a hyperfine splitting in a Delta v=Delta (n-1-1) =2 transition in metastable antiprotonic 4He atoms" Phys.Lett.B. (to be published).
  • Description: 「研究成果報告書概要(欧文)」より
• [Publications] H.A.Torii et al.: "Laser Induced Resonant Transitions in The V=N-L-1=2 and 3 Metastable Cascades of Anti-Protonic He-3 Atoms." Physical Review. A53. 1931-1934 (1996)
• [Publications] B.Ketzer et al.: "Isotope Effects on Delayed Annihilation Time Spectra of Anti-Protonic Helium Atoms in Low Temperature Gas." Phys.Rev.A53. 2108-2117 (1996)
• [Publications] E.Windmann et al.: "Effects of Impurity Atoms and Molecules on The Lifetime of Anti-Protonic Helium Atoms." Phys.Rev.A53. 3129-?? (1996)
• [Publications] T.Yamazaki et al.: "Discovery of deeply bound π states in the ^<208>Pb(d,^3He)" Zeitshrift fur Physik. A355. 219-221 (1996)
• [Publications] R.S.Hayano et al.: "Observation of Double Resonant Laser Induced Transitions in the v=n-1-1=2 Metastable Cascade of Antiprotonic ^4He Atoms" Phys.Rev.A55. 1 (1997)
• [Publications] T.Yamazaki et al.: "Laser resonance studies of the interactions of metastable antiprotonic helium atomcules pbar-^4He^+ with surrounding H_2 molecules" Chem.Phys.Lett.265. 137-144 (1977)
• [Publications] E.Widmann et al.: "Phase and Density Dependence of the Delayed Annihilation of Metastable Antiprotonic Helium Atoms in Gas,Liquid and Solid Helium." Phys.Rev.A51. 2870-2875 (1995)
• [Publications] F.E.Maas et al.: "Laser-induced Resonant Transition at 470.724 nm in the v=n-l-2 Series of Metastable Antiprotonic Helium Atoms." Phys.Rev.A52. 4266-4271 (1995)
• [Publications] H.A.Torii et al.: "Laser Induced Resonant Transitions in the v=n-l-1=2 and 3 Metastable Cascades of Antiprotonic 3He Atomcules." Phys.Rev.A(印刷中). (1996)
• [Publications] B.Ketzer et al.: "Isotope Effects Delayed Annihilation Time Spectra in Antiprotonic Helium Atoms in Low Temperature Gas." Phys.Rev.A(印刷中). (1996)
• [Publications] A.Niestroj to et al.: "Analogue Measurement of Delayed Antiproton Annihilation Time Spectra in a High Intensity Pulsed Antiproton Beam." Nucl.Instr.Meth.A(印刷中). (1996)
• [Publications] S.N.Nakamura et al.: "Delayed Annihilation of Antiprotons in Helium Gas" Phys.Rev.A. 49. 4457 (1994)
• [Publications] N. Morita et al.: "First Observation of Laser-Induced Resonant Annihilation in Metastable Antipratonic Helium Atoms" Phys.Rev.Lett.72. 1180 (1994)
• [Publications] R.S.Hayano et al.: "Laser Studies of the Decay of Metable Antiprotonic Helium Atoms" Phys Rey.Lett.73. 1485 (1994)
• [Publications] T.Yamazaki et al.: "Formation of long-lived gas phase antiprotonic helium atomcules" Nature. 361. 238-240 (1993)
• [Publications] N.Morita et al.: "Laser Spectroscopy of metastable antiprotonic helium atomcules" Nucl.Instr.Methods A. 1330. 439-446 (1993)
• [Publications] E.Widmann et al.: "Antiproton Trapping in Various Helium Media" Nucl Phys.A. 558. 679-688 (1993)
• [Publications] J.Eades: "A naturally occurring trap for antiprotons" Hyperfine Interactions. 81. 227-237 (1993)
• [Publications] N.Morita et al.: "First observation of laser induced resonant annihilation in metastable antiprotonic helium atoms" Phys.Rev.Lett.72. 1180-1183 (1994)
• [Publications] T.Yamazaki: "Production of deeply-bound pionic atoms" Physica Scripta. 48. 169-172 (1993)
• [Publications] S.N.Nakamura et al.: "Delayed annihilation of antiprotons in helium gas" Phys.Rev.(1994)
• [Publications] Y.Ito et al.: "Possible formation of antihydrogen atoms from metastable antiprotonic helium atoms" Hyperfine Interactions. 76. 163-173 (1993)
• [Publications] T.Yamazaki: "Frontiers" Exotic aspects of hadronic atoms-anomalous quasi-stabilities,
• [Publications] T.Yamazaki and K.Ohtsuki: "Atomic Core Polarization Effects in Metastable Hadronic Helium Atoms" Phys.Rev.A45. 7782 (1992)
• [Publications] T.Yamazaki: "Exotic States of Hadronic Atoms" Nucl.Phys.(1993)
• [Publications] Y.Ito,E.Widmann and T.Yamazaki: "Possible Formation of Antihydrogen via Metastable Antiprotonic Helium Atoms and Positrons/Positronium" Hyperfine Interactions. (1993)
• [Publications] T.Yamazaki: "Anomalously Long-Lived Antiprotonic Helium Atoms" AIP Proceedings. (1993)
• [Publications] T.Yamazaki et al.: "Formation of Long-Lived Gas-Phase Antiprotonic Helium Atoms and Quenching by H_2" Nature. 361. 238 (1993)
• [Publications] T.Yamazaki: "Antiproton Trapping in Various Helium Media:Report of the Heliumtrap Experiment at Lear" Nucl.Phys.(1993)
• [Publications] N.Morita,K.Ohtsuki and T.Yamazaki: "Laser Spectroscopy of Metastable Antiprotonic Helium Atomcules" Nucl.Instr.Meth.(1993)
• [Publications] 山崎 敏光: "異常長寿命反陽子" 日本物理学会誌. 47. 470 (1992)
• [Publications] R.S.Hayano and T.Yamazaki: "Perspectives of Meson Science Ch.13" North Holland(Amsterdam), 24 (1992)
• [Publications] R.S.Hayano,M.Iwasaki and T.Yamazaki: "Perspectives of Meson Science Ch.17" North Holland(Amsterdam), 28 (1992)