T. Scharbert

Experiences on the application of the sum-coincidence method

Abstract For the study of cascade γ-processes. Hoogenbooms sum-coincidence method 1 ) has proved exceedingly useful. This method has made it possible to detect transitions of very low intensity, and possesses advantages for measurements of angular correlation as well. As the authors experience shows, in the sum-coincidence spectrum, false peaks or background levels of a certain height may appear in part of the discrimination region. This is partly due to instrumental reasons, partly to the characteristics of the method itself, and it depends on the properties of the decay scheme under study.

Investigations of the decay-scheme of Fe59

Abstract We have examined the gamma-ray spectrum and gamma-gamma coincidence spectrum of Fe59 by means of scintillation spectrometers. The two lines of high energy have been found to be 1.08 and 1.27 MeV respectively. Between these lines no genuine coincidence could be detected. It was the analysis of beta spectrum and beta-gamma coincidence spectra which yielded the beta groups of 275±5 and 455±5 keV end-point energies. The intensity of these was 44.6 and 55.4% respectively, and their corresponding log ft values were 5.3 and 6.1. The relative intensity of the high energy beta transition directly into the ground state was found not to attain 0.5%.

Internal bremsstrahlung in the superallowed decay of the positon emitter 11C

Abstract The internal bremsstrahlung in the superallowed decay of the β + -emitter 11 C has been studied in order to check the fundamental concept of the internal bremsstrahlung process.

Differential spectra of the internal bremsstrahlung from the first-forbidden beta decay of 143Pr and 204Tl

Abstract In the case of both the non-unique first-forbidden 143 Pr decay and the unique first-forbidden 204 Tl decay, the integral measurements performed on the internal bremsstrahlung (IB) spectrum contradict each other and the pertaining theories. On the basis of our differential measurement at 90° carried out with special care to eliminate any possible instrumental distortion effects, it was found that in the case of the IB spectrum from the non-unique first-forbidden decay of 143 Pr, no real deviation from the Nilsson corrected 26 ) KUB 24,25 ) theory seems probable. In the case of the unique first-forbidden decay of 204 Tl, this study confirms the presence of a positive deviation of the experimental IB spectrum from both the allowed and the forbidden theoretical ones in a wide region of the spectrum.

Further γ-spectroscopic investigations on the decay scheme of I131

Abstract Problematic points in the decay scheme of I131 were studied by means of the scintillation and coincidence techniques. The γ-rays at 156 and 210 keV, reported earlier, were recognized to be spurious. The long known γ-ray of 177 keV which does not fit into the decay scheme was found to be in coincidence with a new ray of 326 ± 10 keV. The intensity of this new γ-cascade is ≈ 0.2% in relation to the γ-ray of 364 keV. From the level of 500 ± 10 keV energy corresponding to the sum of the two previous rays in cascade, a cross-over transition occurs also with a relative intensity of 0.8 ± 0.2%. Furthermore it was found that in parallel with the direct transition of 364 keV only the cascade of 80-284 keV is present.

Investigations on the decay scheme of I131 in the low energy region of gamma-rays

Abstract The region below 364 keV energy of gamma radiation deriving from the decay of I131 was examined by scintillation techniques with ordinary as well as with sum-coincidence methods. A new cascade of 156–210 keV (of an intensity of ≈1 % in relation to the cross-over transition) from a level of 364 keV into the ground state was found. Furthermore the existence of the 177 keV line was confirmed by our studies.

Further gamma-spectroscopic inquiry into the decay scheme of Fe59@@@Дальнейшие γ-спектроскопические исследования схемы распада Fe59

The gamma-rays in the decay of Fe59 were examined by the sum-coincidence method. The measurements definitely confirm the existence of the 1.432 MeV level and the 143 as well as the 335 keV gamma-lines. It appears on the other hand that the 1.189, 1.458 and 1.479 MeV levels known from the (p, p’) scattering are not involved in the decay of Fe59. In the case of the 192–1097 keV cascade, the results of the preliminary angular correlation measurements differ from those reported bySchiff andMetzger.РезюмеПри распаде Fe59 γ-лучи были исследованы способом суммированных совпадений. Измерения подтверждают существования уровня 1,432 Мэв и γ-линии с энергией 143 и 335 кэв в паспаде Fe59. С другой стороны выяснено, что уровни с энергией 1,189, 1,458, 1,479 Мэк, которые известны из рассеяния (p, p’), не включены в распад Fe59. Для каскада 192–1097 кэв результаты предварительных измерений угловой корреляции отличаются от результатов, которые были опубликованы Шиффом и Метзгером.

γ−γ angular correlation measurement on the 0,337→1,10 MeV cascade in the decay of Fe59

By applying the scintillation method and sum-coincidence circuit the authors carried out γ−γ angular correlation measurements on the smallest intensity 0,337→1,10 MeV cascade in the decay of Fe59, after having reproduced the results known for the 0,145→1,29 MeV cascade. For the 0,337→1,10 MeV cascade the angular correlation function isW(ν)=1−(0,451±0,156)P2 (cos ν), which for the 1,43, 1,29 and 1,10 MeV levels excludes the spin assignments 3/2, 5/2, 7/2; 5/2, 3/2, 7/2; 3/2, 1/2, 7/2 and 5/2, 1/2, 7/2.РезюмеПрименением сцинтилляционного метода и схемы сум-совпадений после воспроизведения результатов, известных в случае каскада 0,145–1,29 MeV удалось проводить измерения угловой корреляции γ−γ на каскаде 0,337←1,10 MeV наименьшей интенсивности, наблюдаемой в распаде Fe59.Для каскада 0,337 → 1,10 MeV функция угловой корреляцииW(ν)=1−(0,451±0,156)P2 (cos ν), что по отношению уровней 1,43; 1,29 и 1,10 MeV исключает прикрепление к ним спинов 3/2, 5/2, 7/2; 5/2, 3/2, 1/2, 7/2 и 5/2; 1/2, 7/2.

Further gamma-spectroscopic inquiry into the decay scheme of Fe59

The gamma-rays in the decay of Fe59 were examined by the sum-coincidence method. The measurements definitely confirm the existence of the 1.432 MeV level and the 143 as well as the 335 keV gamma-lines. It appears on the other hand that the 1.189, 1.458 and 1.479 MeV levels known from the (p, p’) scattering are not involved in the decay of Fe59. In the case of the 192–1097 keV cascade, the results of the preliminary angular correlation measurements differ from those reported bySchiff andMetzger.РезюмеПри распаде Fe59 γ-лучи были исследованы способом суммированных совпадений. Измерения подтверждают существования уровня 1,432 Мэв и γ-линии с энергией 143 и 335 кэв в паспаде Fe59. С другой стороны выяснено, что уровни с энергией 1,189, 1,458, 1,479 Мэк, которые известны из рассеяния (p, p’), не включены в распад Fe59. Для каскада 192–1097 кэв результаты предварительных измерений угловой корреляции отличаются от результатов, которые были опубликованы Шиффом и Метзгером.

Evaluation process and corrections in the study of the internal bremsstrahlung spectrum accompanying the positive beta-decay of11C

The evaluation and correction procedure for the differential internal bremsstrahlung (IB) spectrum (at 90° between the direction of the beta particle and IB gamma quantum) from the superallowed positron emitter11C (21 min) is described. First a short outline of the theory and the details of the actual experimental arrangement are given and also a comparison is drawn between the theory and the experiment.The whole procedure for the treatment of the experimental data is given and the following corrections are considered in detail: correction for the Compton distribution in the scintillation spectrum, that for the photopeak efficiency and the gamma absorption as well as for beta absorption and concidence efficiency and, finally, for the finite energy resolution of the gamma detector. A number of other corrections and disturbing effects have also been considered shortly.A discussion of the results and the possible errors concludes the article.РезюмеОписываются вычислительные и поправляющие приемы для дифференциального спектра ВТИ (при 90° между направлением бэта-частиц и гамма-кванта ВТИ) из сверхразрешенного позитронного излучателя11C (21 мин.). Вначале дается короткое описание теории и подробные черты новейших экспериментальных оборудований, а далее обсуждается согласие между теорией и опытом.Рассматривается способ интерпретации экспериментальных результатов и подробно дискутируются следующие коррекции: поправки для распределения Комптона в сцинтиляционном спектре, для эффективности в фотопике, как для гамма, так и для бэта абсорций и эффективности совпадения, наконец для конечной энергетической разрешающей способности гамма детектора. Коротко рассматриваются также некоторые другие поправки и эффекты возмущения.Статья заканчивается обсуждением результатов и возможных ошибок.