Photoproduction of pi Mesons between 0.9 and 4.0 BeV

Alvarez, R. ; Bar-Yam, Z. ; Kern, W. ; et al.
Phys.Rev.Lett. 12 (1964) 707-710, 1964.
Inspire Record 944926 DOI 10.17182/hepdata.21825

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1 data table

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Experimental study study of antiproton-proton annihilation into a pair of charged Pi-Mesons or K-Mesons for incident antiproton mementa in the range from 0.72 GeV/c to 2.62 GeV/c

Fong, Douglas G. ; Pine, Jerome ;
RX-294, 1968.
Inspire Record 53368 DOI 10.17182/hepdata.50355

The cross sections for the two antiproton-proton annihilation-in-flight modes, ˉp + p → π+ + π- ˉp + p → k+ + k- were measured for fifteen laboratory antiproton beam momenta ranging from 0.72 to 2.62 GeV/c. No magnets were used to determine the charges in the final state. As a result, the angular distributions were obtained in the form [dσ/dΩ (ΘC.M.) + dσ/dΩ (π – ΘC.M.)] for 45 ≲ ΘC.M. ≲ 135°. A hodoscope-counter system was used to discriminate against events with final states having more than two particles and antiproton-proton elastic scattering events. One spark chamber was used to record the track of each of the two charged final particles. A total of about 40,000 pictures were taken. The events were analyzed by measuring the laboratory angle of the track in each chamber. The value of the square of the mass of the final particles was calculated for each event assuming the reaction ˉp + p → a pair of particles with equal masses. About 20,000 events were found to be either annihilation into π ±-pair or k ±-pair events. The two different charged meson pair modes were also distinctly separated. The average differential cross section of ˉp + p → π+ + π- varied from ~ 25 µb/sr at antiproton beam momentum 0.72 GeV/c (total energy in center-of-mass system, √s = 2.0 GeV) to ~ 2 µb/sr at beam momentum 2.62 GeV/c (√s = 2.64 GeV). The most striking feature in the angular distribution was a peak at ΘC.M. = 90° (cos ΘC.M. = 0) which increased with √s and reached a maximum at √s ~ 2.1 GeV (beam momentum ~ 1.1 GeV/c). Then it diminished and seemed to disappear completely at √s ~ 2.5 GeV (beam momentum ~ 2.13 GeV/c). A valley in the angular distribution occurred at cos ΘC.M. ≈ 0.4. The differential cross section then increased as cos ΘC.M. approached 1. The average differential cross section for ˉp + p → k+ + k- was about one third of that of the π±-pair mode throughout the energy range of this experiment. At the lower energies, the angular distribution, unlike that of the π±-pair mode, was quite isotropic. However, a peak at ΘC.M. = 90° seemed to develop at √s ~ 2.37 GeV (antiproton beam momentum ~ 1.82 GeV/c). No observable change was seen at that energy in the π±-pair cross section. The possible connection of these features with the observed meson resonances at 2.2 GeV and 2.38 GeV, and its implications, were discussed.

2 data tables

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Photoproduction of $\pi^0$ in the Backward Direction

Buschhorn, G. ; Heide, P. ; Kotz, U. ; et al.
Phys.Rev.Lett. 20 (1968) 230-232, 1968.
Inspire Record 54459 DOI 10.17182/hepdata.21735

None

1 data table

No description provided.


Study of neutral final states produced in pi-minus p collisions at momenta of 1.71-2.46 gev/c

Carroll, A.S. ; Corbett, I.F. ; Damerell, C.J.S. ; et al.
Phys.Rev. 177 (1969) 2047-2066, 1969.
Inspire Record 55660 DOI 10.17182/hepdata.5504

We have studied neutral final states produced in π−p collisions at momenta of 1.71, 1.89, 2.07, 2.27, and 2.46 GeVc, by observing the γ rays emitted. In particular, measurements are presented of (i) π−p→π0n, for which the Regge-pole fit at momenta ≥5.9 GeVc also agrees rather well here; (ii) π−p→η0n, for which the Regge model which fits at higher energies does not agree here; (iii) π−p→π0γn, in which there is some evidence for a diffraction dissociation process as well as ω0-meson production; (iv) π−p→π0π0n, which is dominated by production of N*0(1236)π0 and by peripheral production of pion pairs. In (iv), the former process is found to fit with the same Reggeized ρ-meson exchange model as charge-exchange scattering, while the latter gives indication of the s-wave ππ interaction. An account is given of new techniques, particularly in the data analysis, which were developed in the course of this work.

6 data tables

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Study of the charge exchange reaction pi-minus + p ---> pi-neutral + n with the pi-neutral meson backward emission at 1.55-3.8 gev/c

Antipolsky, V.D. ; Bayatyan, G.L. ; Brakhman, E.V. ; et al.
Yad.Fiz. 9 (1969) 1021-1024, 1969.
Inspire Record 56935 DOI 10.17182/hepdata.40403

None

9 data tables

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Photoproduction of positive pions at backward angles in the energy range 1-3 gev

Alvarez, R.A. ; Cooperstein, G. ; Kalata, K. ; et al.
Phys.Rev.D 1 (1970) 1946-1960, 1970.
Inspire Record 61718 DOI 10.17182/hepdata.25170

The cross section for photoproduction of single π+ from hydrogen has been measured at laboratory angles of 110°, 127.5° and 152°, between 0.9- and 3.2-GeV incident photon energy. Measurements have been made with approximately 15% statistical accuracy at about 40 photon energies at each angle. The results agree well with the previous Caltech data of Thiessen. The cross section shows a rapid drop with increasing energy with superimposed bumps or shoulders corresponding to the N(1688), Δ(1920), and Δ(2420). A shallow minimum is observed at the N(2190) resonance.

1 data table

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Coincidence measurements of single pi+ electroproduction

Brown, C.N. ; Canizares, C.R. ; Cooper, W.E. ; et al.
Phys.Rev.Lett. 26 (1971) 987-991, 1971.
Inspire Record 69020 DOI 10.17182/hepdata.21506

We have studied the reaction e−+p→e−+π++n by detecting the final electron and pion in coincidence. Data are presented in the region of virtual photon mass squared from -0.18 to -1.2 GeV2, and virtual photoproduction center-of-mass energy and angle from 1.85 to 2.50 GeV and 0 to 20°, respectively.

12 data tables

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Anti-p p annihilation into pi+ rho at small angles between 1 and 2 gev/c

Yoh, J.K. ; Barish, B. ; Nicholson, H.W. ; et al.
Phys.Rev.Lett. 26 (1971) 922-925, 1971.
Inspire Record 69017 DOI 10.17182/hepdata.21588

We have studied the process p¯p into π+X− using wire spark chambers. The data cover the angular range of cosθp¯π+* between 0.96 and 1.0 at several incident momenta between 1 and 2 GeVc. The reaction p¯p→π+ρ− was observed with (dσdΩ)* of the order of 100 μb/sr at several momenta.

1 data table

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Photoproduction of positive pions at 180 degrees from 0.22 to 3.1 gev

Bouquet, B. ; D' Almagne, B. ; Eschstruth, P.T. ; et al.
Phys.Rev.Lett. 27 (1971) 1244-1247, 1971.
Inspire Record 68896 DOI 10.17182/hepdata.21483

The π+ photoproduction cross section in hydrogen has been measured at 180° for photon energies from 0.22 to 3.1 GeV by detecting the pion in the backward direction. The statistical accuracy of the measurements varies typically from 3 to 10% depending on the energy. The data are compared with other recent experimental results and predictions of phenomenological theories.

1 data table

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Positive-pion photoproduction in the backward direction

Ekstrand, K. ; Browman, A. ; Hand, L. ; et al.
Phys.Rev.D 6 (1972) 1-11, 1972.
Inspire Record 74041 DOI 10.17182/hepdata.3606

The reaction γ+p→π++n has been measured for incident γ-ray energies from 0.7 to 8 GeV and recoil lab angles from 170° to 180° using the Cornell 10-GeV synchrotron. The data presented here cover the transition region between the resonance region and the high-energy region studied at SLAC. The results are compared with various phenomenological Regge-pole analyses and with similar data on π0 photoproduction taken at DESY.

2 data tables

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