Observation of the neutron radiative decay

Khafizov, R. U.; Severijns, N.; Zimmer, O.; Wirth, H. -F.; Rich, D.; Tolokonnikov, S. V.; Соловей, В. А.; Kolhidashvili, M. R.

doi:10.1134/s0021364006010024

Cited by 4 publications

(12 citation statements)

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“…-3 with C.L.=99.7% for radiative gamma quanta with energy over 35 kev [5,6]. Over a year after our first announcement about the results of the conducted experiment, "Nature" [7] published a letter asserting that its authors have also measured the branching ratio of radiative neutron decay B.R.= (3.13±0.34)·10…”

Section: Introductionmentioning

confidence: 99%

“…Fig. 5 shows that the total number of events in e-p coincidences peak in our experiment equals N D =3.75·10 5 . This value exceeds the value we obtained in our previous experiment conducted on beam PF1 at ILL by two orders.…”

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confidence: 99%

“…-3 with C.L.=99.7% and gamma quanta energy over 35 kev [5,6]. A year after our discovery of the radiative neutron decay, a NIST experimental group published the results of their experiment on the study of the radiative neutron decay [7] in Nature, with their own value of B.R.…”

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confidence: 99%

“…Fig. 5 clearly shows two major peaks: one peak with a maximum in channels 99-100, which is the peak of zero or prompt coincidences [5,6,11]. The position of this peak marks the zero time count, namely the time when the electron detector registered the electron.…”

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confidence: 99%

“…However, because we were denied beam time on the intensive cold neutron beam at ILL (Grenoble, France) for a number of years, we could only conduct the experiment in 2005 on the newly opened FRMII reactor of Technical University of Muenchen. The main result of this experiment was the discovery of radiative neutron decay and the measurement of its relative intensity B.R.= (3.2±1.6)·10-3 with C.L.=99.7% for radiative gamma quanta with energy over 35 kev [5,6]. Over a year after our first announcement about the results of the conducted experiment, "Nature" [7] published a letter asserting that its authors have also measured the branching ratio of radiative neutron decay B.R.= (3.13±0.34)·10…”

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Comparison of two experiments on radiative neutron decay

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Over 10 years ago we proposed an experiment on measuring the characteristics of radiative neutron decay in papers [1,2]. At the same time we had published the theoretical spectrum of radiative gamma quanta, calculated within the framework of the electroweak interactions, on the basis of which we proposed the methodology for the future experiment [3,4]. However, because we were denied beam time on the intensive cold neutron beam at ILL (Grenoble, France) for a number of years, we could only conduct the experiment in 2005 on the newly opened FRMII reactor of Technical University of Muenchen. The main result of this experiment was the discovery of radiative neutron decay and the measurement of its relative intensity B.R.= (3.2±1.6)·10-3 with C.L.=99.7% for radiative gamma quanta with energy over 35 kev [5,6]. Over a year after our first announcement about the results of the conducted experiment, "Nature" [7] published a letter asserting that its authors have also measured the branching ratio of radiative neutron decay B.R.= (3.13±0.34)·10-3 with C.L.=68% and gamma quanta energy from 15 to 340 kev. This article aims to compare these two experiments. It is shown that the use of strong magnetic fields in the NIST (Washington, USA) experiment methodology not only prevents any exact measurement of the branching ratio and identification of radiative neutron decay events, but also makes registration of ordinary neutron decay events impossible. PACS numbers: 13.30. Ce; 13.40.Hq; 14.20.Dh Among the many branches of elementary decay with charged particles in the final state, the radiative branch, where the decay occurs with the creation of an additional particle -the gamma quantum, is usually the most intensive, as the relative intensity ( or branching ratio B.R. ) of this mode is determined by the fine structure constant α of 10 -2 order of magnitude. This decay branch is well established and was investigated for almost all elementary particles. However, the radiative decay of the free neutronwas not discovered, and all the experiments were aimed at the study of the ordinary neutron decay branch. We conducted the first experiment on the discovery of this rare neutron decay branch in 2002 on the intensive cold neutron beams at ILL (Grenoble, France), where we received a limit for the relative intensity of this rare decay branch: B.R. < 6.9*10 -3 ( 90% C.L.) [8]. This value exceeds the theoretical value we calculated and published only in by a few times. This fact, in turn, means that in our experiment of 2002 we came very close to discovering the radiative mode of neutron decay. For reasons outside of our control we did not receive beam time on intensive cold neutron beam at ILL for a number of years and were able to continue our experiment only in 2005, after we received beam time at the newly opened FRMII 1

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Comparison of two experiments on radiative neutron decay

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Observation of the radiative decay mode of the free neutron

Nico

Dewey

Gentile

et al. 2006

Nature

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The theory of quantum electrodynamics (QED) predicts that beta decay of the neutron into a proton, electron and antineutrino should be accompanied by a continuous spectrum of soft photons. While this inner bremsstrahlung branch has been previously measured in nuclear beta and electron capture decay, it has never been observed in free neutron decay. Recently, the photon energy spectrum and branching ratio for neutron radiative decay have been calculated using two approaches: a standard QED framework and heavy baryon chiral perturbation theory (an effective theory of hadrons based on the symmetries of quantum chromodynamics). The QED calculation treats the nucleons as point-like, whereas the latter approach includes the effect of nucleon structure in a systematic way. Here we observe the radiative decay mode of free neutrons, measuring photons in coincidence with both the emitted electron and proton. We determined a branching ratio of (3.13 +/- 0.34) x 10(-3) (68 per cent level of confidence) in the energy region between 15 and 340 keV, where the uncertainty is dominated by systematic effects. The value is consistent with the predictions of both theoretical approaches; the characteristic energy spectrum of the radiated photons, which differs from the uncorrelated background spectrum, is also consistent with the calculated spectrum. This result may provide opportunities for more detailed investigations of the weak interaction processes involved in neutron beta decay.

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Calculation of the Geometric Factor in a New Experiment Aimed at Studying Radiative Neutron Decay

Trifonov

Khafizov

2017

Phys. Atom. Nuclei

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Observation of the neutron radiative decay

Cited by 4 publications

References 2 publications

Comparison of two experiments on radiative neutron decay

Comparison of two experiments on radiative neutron decay

Observation of the radiative decay mode of the free neutron

Calculation of the Geometric Factor in a New Experiment Aimed at Studying Radiative Neutron Decay

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