The helicity dependence of the γ→p→→pπ0 reaction has been measured for the first time in the photon-energy range from 550 to 790 MeV. The experiment, performed at the Mainz microtron MAMI, used a 4π-detector system, a circularly polarized, tagged photon beam, and a longitudinally polarized frozen-spin target. These data are predominantly sensitive to the D13(1520) resonance and are used to determine its helicity amplitudes.Received 4 March 2002DOI:https://doi.org/10.1103/PhysRevLett.88.232002©2002 American Physical Society

10.1103/physrevlett.88.232002

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Citations (61)

Status of the IceCube Neutrino Observatory

New Astronomy Reviews (2004)

J. Ahrens John N. Bahcall X. Bai R. C. Bay T. Becka

Neutrino astronomy

Solar neutrino problem

10.1016/j.newar.2003.12.031

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Citations (17)

Investigation of multiparticle final states in12C photoreactions

Physical Review C (1998)

P. D. Harty I. J. D. MacGregor J. Ahrens J. R. M. Annand I. Anthony

The ${}^{12}\mathrm{C}(\ensuremath{\gamma},pn)$, ${}^{12}\mathrm{C}(\ensuremath{\gamma},pp)$, ${}^{12}\mathrm{C}(\ensuremath{\gamma},ppp)$, ${}^{12}\mathrm{C}(\ensuremath{\gamma},pp{\ensuremath{\pi}}^{\ifmmode\pm\else\textpm\fi{}})$, ${}^{12}\mathrm{C}(\ensuremath{\gamma},p{\ensuremath{\pi}}^{\ifmmode\pm\else\textpm\fi{}})$ reactions have been studied using tagged photons of energy ${E}_{\ensuremath{\gamma}}=250$--600 MeV. A model which includes all major absorption mechanisms and final state interactions gives results that agree well with the shapes of missing energy spectra, but for some channels the predicted cross sections are too large.

10.1103/physrevc.57.123

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Citations (12)

Photoemission of protons from 4He in the ⊿-resonance region

Zeitschrift für Physik A Hadrons and Nuclei (1996)

R. Wichmann J. Ahrens H. J. Arends R. Beck G. Galler

Photodisintegration

Photon energy

10.1007/s002180050095

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Photoproduction ofη-MesicHe3

Physical Review Letters (2004)

Masahiro Yoshita J. Ahrens J. R. M. Annand R. Beck G. Caselotti

The photoproduction of η-mesic 3He has been investigated using the TAPS calorimeter at the Mainz Microtron accelerator facility MAMI. The total inclusive cross section for the reaction γ3He→ηX has been measured for photon energies from threshold to 820 MeV. The total and angular differential coherent η cross sections have been extracted up to energies of 745 MeV. A resonancelike structure just above the η production threshold with an isotropic angular distribution suggests the existence of a resonant quasibound state. This is supported by studies of a competing decay channel of such a quasibound η-mesic nucleus into π0pX. A binding energy of (−4.4±4.2) MeV and a width of (25.6±6.1) MeV is deduced for the quasibound η-mesic state in 3He.Received 11 December 2003DOI:https://doi.org/10.1103/PhysRevLett.92.252001©2004 American Physical Society

10.1103/physrevlett.92.252001

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Citations (149)

Test of Low-Energy Theorems for 1H(gamma-vector , pi0)1H in the Threshold Region

P. Achenbach J. Ahrens H. J. Arends Relja Beck A. Schmidt

10.17877/de290r-4542

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Total photoabsorption cross section for4He from 200 to 800 MeV

Physical Review C (1997)

M. MacCormick J. Habermann J. Ahrens G. Audit R. Beck

The total photoabsorption cross section for ${}^{4}$He has been measured for the first time over a wide photon energy range (200 MeV$<~{E}_{\ensuremath{\gamma}}<~$800 MeV). By using the large acceptance detector DAPHNE at the tagged photon facility of the MAMI microtron in Mainz high precision results with small systematic errors were obtained. This measurement shows that ${}^{4}$He has a behavior similar to heavy nuclei and, in particular, a reduction of the cross section with respect to the lighter nuclei is found for ${E}_{\ensuremath{\gamma}}>$600 MeV.

10.1103/physrevc.55.1033

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Citations (27)

The angular distribution of the 12C(γ,pn) reaction for Eγ=120−150 MeV

The European Physical Journal A (1998)

T. Yau I. J. D. MacGregor J. Ahrens J. R. M. Annand R. Beck

Microtron

10.1007/s100500050055

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Citations (18)

EXPERIMENTAL TECHNIQUES FOR PHOTON SCATTERING BELOW 140 MeV.

European Physical Journal A (1971)

D. Mehlig K.H. Czock J. Ahrens Holger Borchert B. Ziegler

Source

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