R. Mermod

Mean life of the neutral pion

High energy neutral mesons( rature of the d ) were produced in platinum foils of 3-60 micron thickness exposed to the 18-Bev internal proton beam of the CERN proton synchrotron, and the production of positrons relative to all heavier particles was measured in a secondary beam of 5-Bev/c. The momentum spectrum of rature of the d /sup o/, which is effective in producing 5Bev/c positrons, is obtained by weighting the rature of the d /sup o/ spectrum with the probability that a positron from a rature of the d /sup o/ has a momentum of 5-Bev/c. The momentum spectra of rature of the d /sup o/ and rature of the d /sup +/ are assumed to be of equal shape and the latter was measured. This effective rature of the d /sup o/ spectrum is narrow and is charactetized by an average momentum of 7.12-Bev/c and a rms momentum of 7.26-Bev/c. The mean life was determined to be (1.05 ction in DDT-C/ 0.18) x 10/sup -16/ sec. (C.E.S.)

A threshold gas Čerenkov counter

Abstract This note describes a type of conventional threshold gas Cerenkov counter, particularly well adapted for the use in high-energy beams. A very simple method has been found to obtain the best collection of the Cerenkov light. When utilized for the detection of 6 GeV/c electrons, its rejection against heavier particles is better than 10−4, and its efficiency better than 99 %.

SEARCH FOR DECAY OF NEUTRAL KAONS INTO CHARGED LEPTON PAIRS.

Abstract A search for decays of K L o and K S o into charged pairs is reported. No event has been found. Upper limits obtained with 90% confidence for the branching ratios are Λ (K L o → μ + μ − )/ Λ (K L o → all) −6 and Λ (K S o → μ + μ − )/ Λ (K S o → all) −5 .

Interference between KL0 and KS0 in the Kμ3 decay mode

Abstract The decay law of a coherent mixture of K L 0 and K S 0 has been studied in the K μ3 mode. The charge asymmetry is analysed as a function of the regeneration phase arg(i ƒ 21 ) and Re(ϵ). In addition arg(i ƒ 21 ) is estimated from recent measurements of K + and K − absorption cross sections in carbon.

Two-pion decay of the long-lived K0 at 10.7 GeV/c

SummaryThe decay rate of KL0 into π+π- has been measured at a mean KL0 momentum of 10.7 GeV/c with the aim to search for an energy dependence. The branching ratio of this decay mode as compared to charged decay modes found in this experiment is (2.12±0.18)·10−3 in agreement with other results of (1.97±0.16)·10−3 at 1.1 GeV/c and (2.08±0.16)·10−3 at 2.5 GeV/c. This result excludes the possibility to maintainCP invariance by introducing a new long-range vector field. From a fit to the branching ratios at different KL0 momenta we obtain an upper limit on an energy splitting between K0 and

Time-dependent interference effects in two-pion decays of neutral kaons

\bar K^0

TOTAL CROSS SECTIONS FOR PIONS ON PROTONS IN THE MOMENTUM RANGE 4.5 TO 10 Gev/c

due to gravitational effects of 1·10−20mKc2 with 90% confidence.RiassuntoSi è misurato il rapporto di decadimento del KL0 in π+π- ad un impulso medio del KL0 di 10.7 GeV/c allo scopo di ricercare una dipendenza dall’energia. Il rapporto di suddivisione di questo modo di decadimento in confronto ai modi di decadimento con carica trovato in questo esperimento è (2.12±0.18)·10−3 che concorda con gli altri risultati (1.97±0.16)·10−3 a 1.1 GeV/c e (2.08±0.16)·10−3 a 2.5 GeV/c. Questo risultato esclude la possibilità di mantenere l’invarianzaCP introducendo un nuovo campo vettoriale di lungo raggio d’azione. Da un’approssimazione ai rapporti di suddivisione a differenti impulsi del KL0 si ottiene un limite superiore per una separazione d’energia fra K0 e