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The Pandemonium effect is a problem that may appear when high resolution detectors (usually germanium detectors) are used in beta decay studies. It can affect the correct determination of the feeding to the different levels of the daughter nucleus. It was first introduced in 1977 paper by J.C. Hardy et al.〔 〕 == Context == Typically, when a parent nucleus beta-decays into its daughter, there is some final energy available which is shared between the final products of the decay. This is called the Q value of the beta decay (''Qβ''). The daughter nucleus doesn't necessarily end up in the ground state after the decay, this only happens when the other products have taken all the available energy with them (usually as kinetic energy). So, in general, the daughter nucleus keeps an amount of the available energy as excitation energy and ends up in an excited state associated to some energy level, as seen in the picture. The daughter nucleus can only stay in that excited state for a small amount of time (the half life of the level) after which it suffers a series of gamma transitions to its lower energy levels. These transitions allow the daughter nucleus to emit the excitation energy in small packages called "gammas". When the daughter nucleus reaches the ground state, it is because it has got rid of all the excitation energy that it kept from the decay. According to this, the energy levels of the daughter nucleus can be populated in two ways: * by direct beta feeding from the beta decay of the parent into the daughter (Iβ), * by gamma transitions of higher energy levels (previously beta-populated from the direct beta decay of the parent) into lower energy levels (ΣIi). The total gamma rays emitted by an energy level (IT) should be equal to the sum of these two contributions, that is, direct beta feeding (Iβ) plus upper-level gamma de-excitations (ΣIi). IT = Iβ + ΣIi (neglecting internal conversion) The beta feeding Iβ (that is, how many times a level is populated by direct feeding from the parent) can not be measured directly. Since the only magnitude that can be measured are the gamma intensities ΣIi and IT (that is, the amount of gammas emitted by the daughter with a certain energy), the beta feeding has to be extracted indirectly by subtracting the contribution from gamma de-excitations of higher energy levels (ΣIi) to the total gamma intensity that leaves the level (IT), that is: Iβ = IT - ΣIi (IT and ΣIi can be measured) 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Pandemonium effect」の詳細全文を読む スポンサード リンク
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