Nonexponential nuclear quantum decay at large times

The framework to describe natural phenomena at their basics being quantum mechanics, there exist a large number of common global phenomena occurring in different branches of natural sciences. One such global phenomenon is spontaneous quantum decay. However, its long time behavior is experimentally poorly known. Here we show, that by combining two genuine quantum mechanical results, it is possible to infer on this large time behavior, directly from data. Specifically, we find evidence for nonexponential behavior of alpha decay of $^{8}\mathrm{Be}$ at large times from experiments.The framework to describe natural phenomena at their basics being quantum mechanics, there exist a large number of common global phenomena occurring in different branches of natural sciences. One such global phenomenon is spontaneous quantum decay. However, its long time behavior is experimentally poorly known. Here we show, that by combining two genuine quantum mechanical results, it is possible to infer on this large time behavior, directly from data. Specifically, we find evidence for nonexponential behavior of alpha decay of $^{8}\mathrm{Be}$ at large times from experiments.

arXiv:nucl-th/0405043Physical Review CAug 17, 200443 citations

Quantum Decay at Long Times

E. Torrontegui, Juan Gonzalo Muga, Joan Martorell +1 more

Advances in quantum chemistryJan 1, 201025 citations

Non-Exponential Decay of Nuclei — A Search for a Fundamental Quantum Effect in Nuclei

Wade W. Scates

AIP conference proceedingsJan 1, 20030 citations

Signature of nonexponential nuclear decay

Amlan Ray, Arindam Kumar Sikdar, A. De

Precision tests of decay law of radioactive nuclei have not so far found any deviation from the exponential decay law at early time, as predicted by quantum mechanics. In this paper, we show that the quantum decoherence time (i.e. the timescale of nonexponential decay) of the quasifission or fission process should be of the order of attosecond considering the atom of the fissioning nucleus as a quantum detector. Hence, the observed decay timescale of the quasifission or fission process of even highly excited (EX greater than 50 MeV) transuranium and uraniumlike complexes should be rather long (of the order of attosecond) in spite of their very fast exponential decay timescale (of the order of zeptosecond) as measured by the nuclear techniques. Recent controversy regarding the observation of very long (of the order of attosecond ) and very short (of the order of zeptosecond ) quasifission or fission timescales for similar systems at similar excitation energies as obtained by direct techniques (crystal blocking, X ray fission fragment) and nuclear techniques could be interpreted as evidence for nonexponential decays in nuclear systemsPrecision tests of decay law of radioactive nuclei have not so far found any deviation from the exponential decay law at early time, as predicted by quantum mechanics. In this paper, we show that the quantum decoherence time (i.e. the timescale of nonexponential decay) of the quasifission or fission process should be of the order of attosecond considering the atom of the fissioning nucleus as a quantum detector. Hence, the observed decay timescale of the quasifission or fission process of even highly excited (EX greater than 50 MeV) transuranium and uraniumlike complexes should be rather long (of the order of attosecond) in spite of their very fast exponential decay timescale (of the order of zeptosecond) as measured by the nuclear techniques. Recent controversy regarding the observation of very long (of the order of attosecond ) and very short (of the order of zeptosecond ) quasifission or fission timescales for similar systems at similar excitation energies as obtained by direct techniques (crystal blocking, X ray fission fragment) and nuclear techniques could be interpreted as evidence for nonexponential decays in nuclear systems

arXiv:1503.05346Mar 18, 20150 citations

Quantum corrections to the decay law in flight

David Fernández Jiménez, Andrés Felipe Guerrero Parra, N. G. Kelkar +1 more

The deviation of the decay law from the exponential is a well known effect of quantum mechanics . Here we analyze the relativistic survival probabilities , S ( t , p ) , where p is the momentum of the decaying particle and provide analytical expressions for S ( t , p ) in the exponential (E) as well as the nonexponential (NE) regions at small and large times. Under minimal assumptions on the spectral density function, analytical expressions for the critical times of transition from the NE to the E at small times and the E to NE at large times are derived. The dependence of the decay law on the relativistic Lorentz factor, γ = 1 / 1 − v 2 / c 2 , reveals several interesting features. In the short time regime of the decay law, the critical time, τ s t , shows a steady increase with γ , thus implying a larger NE region for particles decaying in flight. Comparing S ( t , p ) with the well known time dilation formula, e − Γ t / γ , in the exponential region, an expression for the critical γ where S ( t , p ) deviates most from e − Γ t / γ is presented. This is a purely quantum correction. Under particular conditions on the resonance parameters, there also exists a critical γ at large times which decides if the NE region shifts backward or forward in time as compared to that for a particle at rest. All the above analytical results are supported by calculations involving realistic decays of hadrons and leptons .The deviation of the decay law from the exponential is a well known effect of quantum mechanics . Here we analyze the relativistic survival probabilities , S ( t , p ) , where p is the momentum of the decaying particle and provide analytical expressions for S ( t , p ) in the exponential (E) as well as the nonexponential (NE) regions at small and large times. Under minimal assumptions on the spectral density function, analytical expressions for the critical times of transition from the NE to the E at small times and the E to NE at large times are derived. The dependence of the decay law on the relativistic Lorentz factor, γ = 1 / 1 − v 2 / c 2 , reveals several interesting features. In the short time regime of the decay law, the critical time, τ s t , shows a steady increase with γ , thus implying a larger NE region for particles decaying in flight. Comparing S ( t , p ) with the well known time dilation formula, e − Γ t / γ , in the exponential region, an expression for the critical γ where S ( t , p ) deviates most from e − Γ t / γ is presented. This is a purely quantum correction. Under particular conditions on the resonance parameters, there also exists a critical γ at large times which decides if the NE region shifts backward or forward in time as compared to that for a particle at rest. All the above analytical results are supported by calculations involving realistic decays of hadrons and leptons .

arXiv:2405.03030Annals of PhysicsAug 30, 20240 citations

Transient effects in quantum decay

Gastón García‐Calderón, R. Bijker, Octavio Castaños +2 more

AIP conference proceedingsJan 1, 20110 citations

^{8}\mathrm{Be}

at large times from experiments.