Time Reversal in Nuclear Interactions

Henley, Ernest M.; Jacobsohn, Boris A.

doi:10.1103/physrev.113.225

Cited by 67 publications

(15 citation statements)

References 37 publications

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“…Experiments in nuclear physics [14] have tested the weaker principle of detailed balance [13] which implies jS ab j 2 jS ba j 2 . In the present experiment we test the stronger statement of reciprocity.…”

Section: S Ab S Bamentioning

confidence: 99%

Induced Time-Reversal Symmetry Breaking Observed in Microwave Billiards

et al. 2007

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Using reciprocity, we investigate the breaking of time-reversal (T) symmetry due to a ferrite embedded in a flat microwave billiard. Transmission spectra of isolated single resonances are not sensitive to T violation, whereas those of pairs of nearly degenerate resonances do depend on the direction of time. For their theoretical description a scattering matrix model from nuclear physics is used. The T-violating matrix elements of the effective Hamiltonian for the microwave billiard with the embedded ferrite are determined experimentally as functions of the magnetization of the ferrite.

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Section: S Ab S Bamentioning

confidence: 99%

Induced Time-Reversal Symmetry Breaking Observed in Microwave Billiards

et al. 2007

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“…The observable of detailed balance ([Sabl z-[Sbal2) 2 is not useful because, even in the absence of time reversal invariance, the restriction to only two open channels and the unitarity of the S-matrix cause this quantity to be 0 [24]. Therefore we calculate the antisymmetric part of the Smatrix …”

Section: Calculation Of the Observablementioning

confidence: 99%

Symmetry breaking in statistical nuclear reactions: are two-state-models useful?

Mayer

Müller²,

Harney

1990

Z. Physik A - Atomic Nuclei

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An interesting feature of compound nucleus reactions is that they enhance violations of fundamental symmetries (parity and time reversal). This fact has repeatedly been pointed out in the framework of a two-resonancemodel. Two resonances -isolated from all others do not exist in nuclei. Here, this objection is investigated in a statistical sense. It is shown that the two-level-model yields results that are partly identical, partly quite similar to those from the multi-level-model.

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“…Therefore, the relative strength of the matrix elements of the nuclear Hamiltonian H', which is odd with respect to time reversal, 6 is also (2)(3)(4) xlO" 3 .…”

mentioning

confidence: 98%

Upper Limit ofTNonconservation in the ReactionsMg24+α⇄
Witsch
¹
,
Richter
²
,
Brentano
³

1967
Phys. Rev. Lett.
27
0
9
0
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Time-reversal invariance has been tested via detailed balance in the compound-nuclear reactions 24 Mg+o; ^2 7 Al+p.The relative differential cross sections agree within the experimental uncertainties, leading to an estimated upper limit for the ratio of the Tnonconserving to the T-conserving reaction amplitudes of (2-4) xlO~3. The same upper limit is found for the nuclear matrix elements which are odd with respect to time reversal.Continuing our previous experiments for a search of T-nonconserving effects in compoundnuclear reactions 1 we have studied the reactions 24 Mg + a sr 27 A1 +p under more favorable conditions. We recall briefly the idea of the experiment:A most sensitive test 2 of time-reversal invariance by detailed balance should be provided by a reaction proceeding via a compound nucleus which is excited in the region of strongly overlapping levels. The interference of many coherently excited resonanced then gives rise to statistical fluctuations of the cross section as a function of energy. In the presence of a time-reversal-odd force the reaction amplitude can be split into a T-conserving and a small T-nonconserving part which are assumed to fluctuate independently of each other. 3 This implies that the T-odd part of the amplitude should be enhanced relative to the T-even one at a minimum of the cross section where the time-reversal-even amplitude is reduced. The most favorable case, of course, will be a reaction where only one single spin channel contributes to the cross section. This is true for the two reactions 24 Mg + a^=-27 A1 +p at 0 = 0° and 0 = 180°. The experiment consisted in the measurement of excitation functions at an angle 6 C m =172.6°, where the admixture of further amplitudes was estimated to be less than 10%.The a particles and protons were accelerated by the Heidelberg tandem Van de Graaff. Great effort was made to minimize the background in the spectra. The very carefully prepared targets (15 mm in diameter) consisted of isotopically enriched magnesium (99.96% 24 Mg, 33 jig/cm 2 ) evaporated onto thin carbon foils and of self-supporting aluminum (35 /ig/ cm 2 ), respectively. The a particles were detected with silicon surface-barrier counters, the protons with lithium-drifted silicon counters, both of them cooled to about -40°C. In the (a>p) measurement, 8-and 9-/i-thick aluminum foils were placed in front of the counters in order to shift a particles to the lowenergy end of the spectrum. All other experimental arrangements were the same as in the previous measurements. 1 The cross sections in both reactions were taken at a very high maximum at Ep ~ 10.3 MeV and E a ~ 13.45 MeV and at two other energies, viz. a rather wide minimum at Ep~ 10.55 MeV and E a ~13.73 MeV and a second maximum at E p -11.3 MeV and E a~ 14.6 MeV. In order to avoid the measurement of absolute values, the cross sections of the two reactions were normalized in the high maximum (Fig. 1) and then compared with each other in the minimum and in the second maximum. Since the energy spread in the entrance c...

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Time Reversal in Nuclear Interactions

Cited by 67 publications

References 37 publications

Induced Time-Reversal Symmetry Breaking Observed in Microwave Billiards

Induced Time-Reversal Symmetry Breaking Observed in Microwave Billiards

Symmetry breaking in statistical nuclear reactions: are two-state-models useful?

Upper Limit ofTNonconservation in the ReactionsMg24+α⇄
Witsch
¹
,
Richter
²
,
Brentano
³

1967
Phys. Rev. Lett.
27
0
9
0
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Time Reversal in Nuclear Interactions

Cited by 67 publications

References 37 publications

Induced Time-Reversal Symmetry Breaking Observed in Microwave Billiards

Induced Time-Reversal Symmetry Breaking Observed in Microwave Billiards

Symmetry breaking in statistical nuclear reactions: are two-state-models useful?

Upper Limit ofTNonconservation in the ReactionsMg24+α⇄Witsch1, Richter2, Brentano3 1967Phys. Rev. Lett.27090View full textAdd to dashboardCite

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Upper Limit ofTNonconservation in the ReactionsMg24+α⇄
Witsch
¹
,
Richter
²
,
Brentano
³

1967
Phys. Rev. Lett.
27
0
9
0
View full text Add to dashboard Cite