Reactions of StoppingK−in Helium

Abstract

Branching ratios have been measured for reactions initiated by negative kaons coming to rest in a helium bubble chamber. The data were obtained from an analysis of -1000 events found in a careful scan using a very limited fiducial volume. Charged2 emission accounts for (30.8~k3.2)7~ of the absorptions and A/ZO emission for (69.2&6.6)%. Evidence for Z-to-A conversion is clearly seen in the events with a visible A+r-, and (66&9)y0 of this final state results from such a process. Multinucleon (i.e., nonpionic) absorption is found to occur in (16.53~2.6)7~ of the events, which is similar to the results reported from studies using heavy-liquid bubble chambers and nuclear emulsion. In general, the kinematic spectra for single-nucleon absorption events agree well with the predictions of a simple impulse approximation. The ratio of Kcapture on neutrons to that on protons is examined using the An-He3 and the An0H3 final states. The data for charged-and neutral-particle emission are consistent with the predictions of isospin invariance for kaon absorption in He4.

Deeply boundK−ppstate in theHe3(in-flightKoike1, Harada2 2009Phys. Rev. C171130View full textAdd to dashboardCite

“…This value is often used in previous works for heavier targets [26,27,41,42] but it is experimentally unknown in the K − absorption on 3 He in flight. In terms of the K − absorption on 4 He at rest, the early data of the helium bubble chamber experiment [47] suggested that the ratio of the two-nucleon K − absorption to all the K − absorption processes amounts to 16 %, whereas its value depends on atomic orbits where K − is absorbed through atomic cascade processes [27,48]. A recent analysis of the …”

Study of the Σ0p Final State from K− Absorptions

“…Hence the study of the interaction is entangled with the absorption processes that should be understood quantitatively. One of the main questions when dealing with absorption processes is the specific contribution of processes involving two, three or more nucleons, for which several reactions have been investigated [1] ( e.g. K − + 4 He, K − + 3 He, K − + 12 C..) to extract this information.…”

Search for a boundK−ppsystem

“…The Σ 0 could subsequently decay into Λγ generating a signal in the Λp invariant mass at an energy which could be roughly compatible with the experimental bump. However, the relative branching fractions of the two channels is Λp/Σ 0 p ∼ 4 [11], which suggests that only a minor fraction of the total strength should be originated by Σ 0 p pairs. (Λp) invariant mass spectrum after K − absorption on 6 Li, 7 Li and 12 C targets of FINUDA [20].…”

“…Still, experimental results on K − absorption on 2 or more nucleons are rather scarce in literature, with a relevant part of the experimental data produced by old bubble chamber experiments [10][11][12] which didn't have a good enough resolution to study high momentum (≥ 400-500MeV/c) protons and Λ's.…”