| 1. |
- Ahrens, J, et al.
(author)
-
Helicity dependence of the (gamma)over-right-arrow (p)over-right-arrow -> n pi(+) pi(0) reaction in the second resonance region
- 2003
-
In: Physics Letters. Section B: Nuclear, Elementary Particle and High-Energy Physics. - 0370-2693. ; 551:1-2, s. 49-55
-
Journal article (peer-reviewed)abstract
- The helicity dependence of the total cross section for the (γ) over right arrow(p) over right arrownpi(+) pi(0) reaction has been measured for the first time at incident photon energies from 400 to 800 MeV The measurement was performed with the large acceptance detector DAPHNE at the tagged photon beam facility of the MAMI accelerator in Mainz. This channel is found to be excited predominantly when the photon and proton have a parallel spin orientation, due to the intermediate production of the D-13 resonance. (C) 2002 Elsevier Science B.V. All rights reserved.
|
|
| 2. |
- Ahrens, J, et al.
(author)
-
Intermediate resonance excitation in the gamma p -> p pi(0)pi(0) reaction
- 2005
-
In: Physics Letters. Section B: Nuclear, Elementary Particle and High-Energy Physics. - : Elsevier BV. - 0370-2693. ; 624:3-4, s. 173-180
-
Journal article (peer-reviewed)abstract
- The helicity dependence of the total cross section for the (gamma) over right arrow(p) over right arrow -> p pi(0)pi(0) reaction has been measured for the first time at incident photon energies from 400 to 800 MeV. The measurement, performed at the tagged photon beam facility of the MAMI accelerator in Mainz, used the large acceptance detector DAPHNE and a longitudinally polarized frozen-spin target. This channel is found to be excited predominantly when the photon and proton have a parallel spin orientation, most likely due to the intermediate production of the D-13(1520) resonance. However, the contribution of the antiparallel spin configuration, arising from other reaction mechanisms, is also not negligible. This result gives important new information to resolve the existing model discrepancies in the identification of the nucleon resonances contributing to this channel.
|
|
| 3. |
- Dutz, H, et al.
(author)
-
Experimental check of the Gerasimov-Drell-Hearn sum rule for H-1
- 2004
-
In: Physical Review Letters. - 1079-7114. ; 93:3
-
Journal article (peer-reviewed)abstract
- For the first time we checked the fundamental Gerasimov-Drell-Hearn (GDH) sum rule for the proton experimentally in the photon energy range from 0.2-2.9 GeV with the tagged photon facilities at MAMI (Mainz) and ELSA (Bonn). New data of the doubly polarized total cross section difference are presented in the energy range from 1.6 to 2.9 GeV. The contribution to the GDH integral from 0.2-2.9 GeV yields [254+/-5(stat)+/-12(syst)] mub with negative contributions in the Regge regime at photon energies above 2.1 GeV. This trend supports the validity of the GDH sum rule.
|
|
| 4. |
- Dutz, H, et al.
(author)
-
First measurement of the Gerasimov-Drell-Hearn sum rule for H-1 from 0.7 to 1.8 GeV at ELSA
- 2003
-
In: Physical Review Letters. - 1079-7114. ; 91:19: 192001
-
Journal article (peer-reviewed)abstract
- To verify the fundamental Gerasimov-Drell-Hearn (GDH) sum rule for the first time experimentally, we measured the helicity dependent total photoabsorption cross section with circularly polarized real photons and longitudinally polarized nucleons in the photon energy range 0.68-1.82 GeV with the tagged photon facility at ELSA. The experiment was carried out with a 4pi detection system, a circularly polarized tagged photon beam, and a frozen spin polarized proton target. The contribution to the GDH sum rule in this photon energy range is [49.9+/-2.4(stat)+/-2.2(syst)] mub.
|
|
| 5. |
- Dutz, H, et al.
(author)
-
Measurement of helicity-dependent photoabsorption cross sections on the neutron from 815 to 1825 MeV
- 2005
-
In: Physical Review Letters. - 1079-7114. ; 94
-
Journal article (peer-reviewed)abstract
- Helicity-dependent total photoabsorption cross sections on the deuteron have been measured for the first time at ELSA (Bonn) in the photon energy range from 815 to 1825 MeV. Circularly polarized tagged photons impinging on a longitudinally polarized LiD target have been used together with a highly efficient 4 pi detector system. The data around 1 GeV are not compatible with predictions from existing multipole analyses. From the measured energy range an experimental contribution to the GDH integral on the neutron of [33.9 +/- 5.5(stat)+/- 4.5(syst)] mu b is extracted.
|
|
| 6. |
- Aguar-Bartolome, P., et al.
(author)
-
Measurement of the gamma p -> K-0 Sigma(+) reaction with the Crystal Ball/TAPS detectors at the Mainz Microtron
- 2013
-
In: Physical Review C (Nuclear Physics). - 0556-2813. ; 88:4
-
Journal article (peer-reviewed)abstract
- The gamma p -> K-0 Sigma(+) reaction has been measured from threshold to E-gamma = 1.45 GeV (W-CM = 1.9 GeV) using the Crystal Ball and TAPS multiphoton spectrometers together with the photon tagging facility at the Mainz Microtron MAMI. In the present experiment, this reaction was searched for in the 3 pi(0)p final state, by assuming K-S(0) -> pi(0)pi(0) and Sigma(+) -> pi(0)p. The experimental results include total and differential cross sections as well as the polarization of the recoil hyperon. The new data significantly improve empirical knowledge about the gamma p -> K-0 Sigma(+) reaction in the measured energy range. The results are compared to previous measurements and model predictions. It is demonstrated that adding the present gamma p -> K-0 Sigma(+) results to existing data allowed a better description of this reaction with various models.
|
|
| 7. |
- Aguar-Bartolome, P., et al.
(author)
-
New determination of the eta transition form factor in the Dalitz decay eta -> e(+) e(-) gamma with the Crystal Ball/TAPS detectors at the Mainz Microtron
- 2014
-
In: Physical Review C (Nuclear Physics). - 0556-2813. ; 89:4
-
Journal article (peer-reviewed)abstract
- The Dalitz decay eta -> e(+) e(-) gamma has been measured in the gamma p -> eta p reaction with the Crystal Ball and TAPS multiphoton spectrometers, together with the photon-tagging facility at the Mainz Microtron MAMI. The experimental statistic used in this work is one order of magnitude greater than in any previous measurement of eta -> e(+) e(-) gamma. The value obtained for the slope parameter Lambda(-2) of the eta transition form factor, Lambda(-2) = (1.95 +/- 0.15(stat) +/- 0.10(syst)) GeV-2, is in good agreement with recent measurements conducted in eta -> e(+) e(-) gamma and eta -> mu(+) mu(-) gamma decays, as well as with recent form-factor calculations. The uncertainty obtained in the value of Lambda(-2) is lower compared to results from previous measurements of the eta -> e(+) e(-) gamma decay.
|
|
| 8. |
- Kashevarov, V. L., et al.
(author)
-
Experimental study of the gamma p -> pi (0)pi(0) p reaction with the Crystal Ball/TAPS detector system at the Mainz Microtron
- 2012
-
In: Physical Review C (Nuclear Physics). - 0556-2813. ; 85:6
-
Journal article (peer-reviewed)abstract
- The gamma p -> pi(0)pi(0) p reaction has been measured from threshold to 1.4 GeV using the Crystal Ball and TAPS photon spectrometers together with the photon tagging facility at the Mainz Microtron. The experimental results include total and differential cross sections as well as specific angular distributions, which were used to extract partial-wave amplitudes. In particular, the energy region below the D-13(1520) resonance was studied.
|
|
