Search for spontaneous ??- emission from a252Cf source

Abstract

High energy np-pairs from a 2s2Cf source were searched for. They are expected to be emitted with the absorption of negative pions which can be created through spontaneous fissions. The branching ratio is deduced as /'~-/ff'SF < 1.3x10 -8 at the confidence level of 90%.PACS: 25.85.Ca; 27.90. + bWe searched for a spontaneous emission of negative pions. Since the Q. calculated by a mass formula is small, an emitted pion is expected to interact with a nucleus nearby. The pion is mainly absorbed by two correlated nucleons in the nucleus [5]. An np-pair is emitted at about 180 ~ (back to back) when the pion is absorbed by a pppair in the nucleus. Each nucleon of the pair is supposed to have a kinetic energy of about 70 MeV. It was the purpose of this experiment to search for such high energy np-pairs from a 252Cf source ~.

Evaluation of the Prompt Gamma-ray Spectrum from Spontaneous Fission of 252Cf

“…37 10 -11 with a 90% confidence level [107]. H. Otsu 1992 Tokyo 6.9 10 +5 π -→ np (≈ 70 MeV) Si solid detector followed by NaI(Tl) Γπ-/Γsf < 1.3 10 -8 [111] The bottom part of Table 8.1 additionally lists the few known measurements of the charged pions (π + or π -) or muons (μ + or μ -) emission probability relative to 252 Cf spontaneous fission [108] - [111]. In these experiments the primary muons from 252 Cf(s.f.)…”

A simplified spectrometer based on a fast digital oscilloscope for the measurement of high energy γ-rays

“…The study of energy and angular spectra of high energy γ-rays emitted in the spontaneous fission of heavy nuclei remains one of the most attractive ways to create a complete picture of the evolution of the fissioning system (emission of prescission γ-rays [1], excitation of giant dipole resonances in fission fragments [1,2]), and to search for exotic radioactivity of heavy nuclei [3,4]. While the emission process of γ-rays and neutrons with energies E γ ≤ 10 .…”