Test of the Zweig selection rule in Φ production by pp collisions

http://shop-pdp.net/efhtml/NIM_105_1972_573-584_Drosg.pdf

ACCURATE MEASUREMENT OF THE COUNTING EFFICIENCY OF A NE-213 NEUTRON DETECTOR BETWEEN 2 AND 26 MeV.

A compilation of n-p and n-C cross sections and their use in a Monte Carlo program to calculate the neutron detection efficiency in plastic scintillator in the energy range 1–300 MeV

SummaryA new fit to the world data on (ep) and (en) elastic scattering, and on (\n$$\\bar p$$\np) annihilation into lepton pairs, has been obtained by using a model for the isovector and isoscalar nucleon form factors, which is suggested by the use of unitary symmetry and of its breaking. The fit allows for a nonpointlike behaviour of one out of the two couplings which enter in the expression for nucleon electromagnetic form factors. The fit is a one-parameter fit and the corresponding values ofχ2 for the proton and neutron data are discussed. The contributions coming from the possible existence of « core-terms » and of «q2-dependent background » in the expression of the nucleon electromagnetic form factors are found to be lower than a few per cent. Theq2 dependence of the vector-meson-nucleon couplings is also discussed.RiassuntoSi è ottenuta una nuova approssimazione ai dati universali sullo scattering elastico (ep) e (en) e sulla annichilazione (\n$$\\bar p$$\np) in coppie di leptoni, facendo uso di un modello per i fattori di forma isovettoriali ed isoscalari del nucleone, suggerito dall’uso della simmetria unitaria e della sua infrazione. L’approssimazione tiene conto del comportamento non puntiforme di uno dei due accoppiamenti che entrano nell’espressione dei fattori di forma elettromagnetici del nucleone. L’approssimazione è ad un solo parametro e si discutono i corrispondenti valori di χ2 per i dati dei protoni e dei neutroni. Si trova che i contributi derivanti dalla possibile esistenza di « core terms » e di « un fondo dipendente da ϱ2 » nell’espressione dei fattori di forma elettromagnetici del nucleone sono inferiori ad alcuni percento. Si discute anche la dipendenza daq2 dell’accoppiamento mesone vettoriale-nucleone.

One-paramenter fit to the electromagnetic form factors of the nucleon

We glance back at the short period of the great discoveries between 1970 and 1974 that led to the restablishment of Quantum Field Theory and the discovery of the Standard Model of Elementary Particles, in particular Quantum Chromodynamics, and ask ourselves where we stand now.

When was asymptotic freedom discovered? or The rehabilitation of quantum field theory

A large-acceptance and high-efficiency neutron detector is described. The sensitive surface and volume of the detector are 2.16 m2 and 0.78 m3, respectively. The detector consists of twenty-four elements of plastic scintillator, each having dimensions (100×18×18) cm3. The large volume of scintillator, in the particular geometrical arrangement chosen, allows a mean detection efficiency of about 25% in the range (70÷390) MeV neutron kinetic energy for a laboratory solid angle of 0.14 sr at 4 m radial distance. With the techniques adopted, calibrations with charged particles can be easily performed in a few hours using a low beam intensity. An interesting features of this instrument is the accuracy achieved in locating incident particles, which is ±1.4 cm for charged particles, and ±2.5 cm for neutrons. The accuracies achieved for the time-of-flight measurement are ±0.35 ns for charged particles and ±0.7 ns for neutrons. With these resolutions in the neutron time of flight and angle, the uncertainty in the missing mass is ±4 MeV for η, ±10 MeV for ω, and ±15 MeV for ϕ mesons.

A new large-acceptance and high-efficiency neutron detector for missing-mass studies

A evidence for a new decay mode of the X0-meson: X0→2γ

/pdf/observation-of-the-rare-decay-mode-of-the-ph-meson-ph-e-e-3anz00pkid.pdf

Observation of the rare decay mode of the φ-meson: φ→e+e−

/pdf/the-decay-mode-o-e-e-and-a-direct-determination-of-the-o-ph-baq7canb6u.pdf

A. Buhler-Broglin

Papers

A new large-acceptance and high-efficiency neutron detector for missing-mass studies

A evidence for a new decay mode of the X0-meson: X0→2γ

Observation of the rare decay mode of the φ-meson: φ→e+e−

The decay mode ω→e + e − and a direct determination of the ω-ϕ mixing angle

Search for charges 1/3e and 2/3e in the cosmic radiation