Low-Energy Antiproton Interactions in Hydrogen and Deuterium

Horwitz, N.; Miller, Don R.; Murray, Joseph J.; Tripp, Robert D.

doi:10.1103/physrev.115.472

Cited by 42 publications

(10 citation statements)

References 11 publications

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“…10 In this experiment we have observed some 500 annihilations. Detailed meas urements were possible on 437 annihilations, of which 140 fit require ments of annihilation on hydrogen.…”

Section: Results: the Annihilation Process A Observation Of Annihmentioning

confidence: 88%

“…-12-quantity I = 52,000 indicates that 52,000 particles for each 10 10 protons hitting the target were obtained by integrating over the useful beam area.…”

Section: A the Antiproton Beammentioning

confidence: 99%

“…[2][3][4][5][6][7][8][9] In addition, a hydrogen-bubble-chamber experiment was recently performed. 10 A thorough review of the experimental and theoretical developments on antinucleons has been given recently by Segrè. 11 Among the antiproton's interesting properties which have been observed are:…”

Section: Introductionmentioning

confidence: 99%

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Antiproton Interactions in Hydrogen and Carbon below 200 Mev

et al. 1960

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“…10 In this experiment we have observed some 500 annihilations. Detailed meas urements were possible on 437 annihilations, of which 140 fit require ments of annihilation on hydrogen.…”

Section: Results: the Annihilation Process A Observation Of Annihmentioning

confidence: 88%

“…-12-quantity I = 52,000 indicates that 52,000 particles for each 10 10 protons hitting the target were obtained by integrating over the useful beam area.…”

Section: A the Antiproton Beammentioning

confidence: 99%

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Antiproton Interactions in Hydrogen and Carbon below 200 Mev

et al. 1960

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“…This pion toen proceeds to inittote reactions (5) and (6 No precise quaatitative results were obtaiaed for the aagular distributioa of aatiprotoas produced at a givea momeatum. Qualitotively, we found to our momeatuna raage that toe productioa cross sectioa at " 10 deg to the laboratory system was about 12% smaller than toe cross section at 0 deg.…”

Section: -$'mentioning

confidence: 99%

Antiproton-Nucleon Cross Sections from 0.5 to 1.0 BeV

et al. 1962

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“…This weight was equal to, the reciprocal of the average probability that the antinucleon from such an event would produce an annihilation with more than two charged prongs in the 7 2-inch chamber. After weighting the events, correcting for scanl'lning efficiencies, and making use of the known p-p total cross sections, ( 1) and (4) are equal. On the basis of the assumption that they are indeed equal, the total inelastic cross section is u 1 1 ti : 5.3::1 mb.…”

Section: The Inelastic Eventsmentioning

confidence: 99%

Final States of the Antiproton-Proton System

Lynch

1961

Rev. Mod. Phys.

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This paper reports some of the results from two antiproton experiments which were the first major experiments performed with the Alvarez 7Z-inch hydrogen bubble chamber. The beam momentum at the center of the chamber w,as 1.61 Bev/c for the first experiment and 1.9·9 Bev/c for the second. Details 1 of these beams have been published elsewhere. Rare Two-Body Final StatesA primary motivation for the choice of these momenta was that 1.61 Bev/c is above the threshold for the reaction p + p + A+ A, and 1.99 Bev/c is above the thresholds for producing antieigma particles. In a total of about Zl, 000 antiproton interactions at 1.61 Bev/c there were found 11 events of the A A reaction. Figure 1 shows the first one of these events found. This one was unusually easy to identify because both the A and the A decayed via the charged mode and the antiproton from the A decay annihilated within the chamber. At 1.61 Bev/c the cross section for this reaction is 57 :t: 18 j.lb. At the higher momentum, in addition to two events of the A A reaction, there were (among about 5000 amtiproton int:eTactions) twoevents which were either p + p-:I; + A or 1: + ~1..There are two other rare two-body final states in p-p interactions, namely -+ --+ -the annihilation into two pions or two kaons: p + p-'11' + '11' or p + p-K + K .Neither of these reactions had been observed among the many thousands of antiproton interactions ~tudied bf.ilore this experiment.This fact has been considered mysterious, 2 and has led to some speculation about possible selection rules against these reactions. Actually there have beenreported only about 600 events 3 • 4 that could be attributed to antiproton inter-·• actions with free protons and among which these two-body reactions have been sought. In view of the fact that the average pion multiplicity in antiproton anni-.' bilations is about five, it is not surprising that this rate is so small. Figure Z ..shows the prediction of the Fermi statistical model (using a Lorentz-invariant phase space) for the ratio of the number of annihilations resulting in two charged pions and no neutral ones, to the number of all annihilations in which kaons are not produced. Although this ratio is plotted only for the energy of this experiment, it has wider applicability because for a given multiplicity this ratio, as well as most other statistical-model predictions, is quite insensitive to the center-of-mass energy.A search was made for these events among the approximately 13, 000 two-... ·•ptong events in the film. All but lZS of these were easily eliminated by crude measurements on the scanning table. These lZS events were measured with the Franckenstein measuring projector and kinematically analyzed. Figure 3 shows the z + + ..x distribution for the events for the tests of the 1T v and the K K hypotheses. zEvents not shown on the plots had x greater than 100.The mean of these distributions is about twice the mean expected value (four), for these four-constraint fits. This is an indication that the assigned errors were underesti...

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Low-Energy Antiproton Interactions in Hydrogen and Deuterium

Cited by 42 publications

References 11 publications

Antiproton Interactions in Hydrogen and Carbon below 200 Mev

Antiproton Interactions in Hydrogen and Carbon below 200 Mev

Antiproton-Nucleon Cross Sections from 0.5 to 1.0 BeV

Final States of the Antiproton-Proton System

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