Spontaneous pion emission as a new natural radioactivity

Ion, D.B.; Ivaşcu, M.; Ion-Mihai, R.

doi:10.1016/0003-4916(86)90001-1

Cited by 21 publications

(15 citation statements)

References 28 publications

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“…The large amount of energy available in the fissioning system ( 185 MeV) has motivated numerous experiments looking for the emission of high energy p rays [1], neutral pions [2 -4], and charged pions [5]. In an amazing series of experiments [5,6] Ion and his collaborators have reported searching for various radioactivities from the spontaneous fission of~5 2Cf. They looked for x+, p+, and have even suggested the possible existence of natural strange radiation in the form of the spontaneous emission of Ao (mgo = 1116 MeV).…”

Section: Introductionmentioning

confidence: 99%

Search for high energy γ rays from the spontaneous fission ofCf252

Gossett

Vandenbosch

1991

Phys. Rev. C

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We have searched for high energy p rays emitted from the spontaneous fission of Cf. This search was carried out by two methods: the measurement of high energy p rays in coincidence with fission fragments, and the measurement of high energy p rays in coincidence with any other p ray. The first of these two methods allowed us to establish a direct correlation between high energy p rays and fission fragments. For the fission-fragment/y-ray measurement, we were able to set an upper limit at the 95/0 confidence level of 1.8 x 10 photon per fission for the integrated yield of p rays with an energy greater than 30 MeV. Additionally, we have established an upper limit at the 95+0 confidence level of 1.0 x 10 photon per fission for the integrated yield of photons with energy greater than 30 MeV from the p-p measurement. These results are shown to be consistent with a classical model estimate of the upper limit of p rays produced by a nucleus-nucleus bremsstrahlung process arising from the Coulomb acceleration of the fission fragments.

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Section: Introductionmentioning

confidence: 99%

Search for high energy γ rays from the spontaneous fission ofCf252

Gossett

Vandenbosch

1991

Phys. Rev. C

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“…Recently a possibility of a spontaneous emission of a pion was investigated [1][2][3][4]. The spontaneous pion emission from a ground state of a nucleus is not allowed by the conservation of energy and momentum through a decay to two body final state, but is allowed through a decay to three or more body final state.…”

Section: Introductionmentioning

confidence: 99%

Search for spontaneous ??- emission from a252Cf source

Otsu

Sakamoto

Okamura

et al. 1992

Z. Physik A - Hadrons and Nuclei

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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 ~.

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“…More recently, the pionic nuclear radioactivity or spontaneous pion emission by a nucleus from its ground state was investigated [5]. This kind of radioactivity is only possible via three body final state channels.…”

Section: Introductionmentioning

confidence: 99%

“…To emit pions as free particles, sufficient energy must be imparted to the nucleus to create their rest mass. The authors [5] consider the following reaction: Experimental evidence for spontaneous pion emission from the ground state of 252Cf was recently published [8] after analysing the experimental data of Whetstone and Thomas [9]-The inferred ratio F~ § VSF> 6.10 -4 is surprisingly very large. However it is rather difficult to distinguish between electrons and charged pions (or muons) if the detection system is not suitable.…”

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confidence: 99%

“…Rose and Jones reported the emission of I&C nuclei from 223 Ra with a branching ratio of 8.5 -2.5 i0 -I~ relative to ~ particles. Two theoretical models have been proposed [5,4] which share the assumption that intermediate mass spontaneous emission can be described by a barrier penetration process similar to spontaneous fission.More recently, the pionic nuclear radioactivity or spontaneous pion emission by a nucleus from its ground state was investigated [5]. This kind of radioactivity is only possible via three body final state channels.…”

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confidence: 99%

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Search for spontaneous pion emission from252Cf source

Cerruti¹,

Hisleur

Julien

et al. 1988

Z. Physik A - Atomic Nuclei

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Abstract:An experiment was carried out at Saclay, in order to determine the ratio F~/ FSF with a 252 Cf source. An upper limit to this ratio is obtained, but the existence of spontaneous pion emission phenomenon is still an open question.The spontaneous emission of fragments from nuclei is now well established [1,2] : some radioactive ~ sources like Ra and U isotopes can emit 14C, 2L'25Ne,....fragments with branching ratios of i0 -I~ relative to the ~ particles. Rose and Jones reported the emission of I&C nuclei from 223 Ra with a branching ratio of 8.5 -2.5 i0 -I~ relative to ~ particles. Two theoretical models have been proposed [5,4] which share the assumption that intermediate mass spontaneous emission can be described by a barrier penetration process similar to spontaneous fission.More recently, the pionic nuclear radioactivity or spontaneous pion emission by a nucleus from its ground state was investigated [5]. This kind of radioactivity is only possible via three body final state channels. In this sense, it is different from the spontaneous emission of elementary particles (w, electron...) or spontaneous emission of nuclear clusters (~,IAC .... )The conservation of energy and momentum forbids the spontaneous emission of pions from a ground state nucleus via two body final state decay mode. To emit pions as free particles, sufficient energy must be imparted to the nucleus to create their rest mass. Experimental evidence for spontaneous pion emission from the ground state of 252Cf was recently published [8] after analysing the experimental data of Whetstone and Thomas [9]-The inferred ratio F~ § VSF> 6.10 -4 is surprisingly very large. However it is rather difficult to distinguish between electrons and charged pions (or muons) if the detection system is not suitable. In the spontaneous pion phenomenon, the pion energy is small and the charged pion identification presents considerable difficulties.0n the other hand, neutral pion identification, through the detection of the two 68 MeV gammas emitted at 180 degrees, gives more credible data.An experiment was carried out at Saclay, in order to determine the ratio F~ /FSF with a252Cf source. Two lead glass detectors were used to count gamma rays issued from the neutral pion decay. The response, the efficiency and the resolution of these detectors were studied pre-

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Spontaneous pion emission as a new natural radioactivity

Cited by 21 publications

References 28 publications

Search for high energy γ rays from the spontaneous fission ofCf252

Search for high energy γ rays from the spontaneous fission ofCf252

Search for spontaneous ??- emission from a252Cf source

Search for spontaneous pion emission from252Cf source

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