| 1. |
- Coron, N., et al.
(författare)
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A Composite Bolometer as a Charged-Particle Spectrometer
- 1985
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Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 314:6006, s. 75-76
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Tidskriftsartikel (refereegranskat)abstract
- The measurement of radioactivity by direct conversion of nuclear radiation into a temperature rise of a calorimeter is as old as nuclear physics itself. As part of a general programme aiming at a determination of the mass of the electron neutrino, we have designed an improved version of a He-cooled composite diamond bolometer with a monolithic germanium thermistor, developed at the Laboratoire de Physique Stellaire et Planetaire (LPSP)1. Our approach, based on an idea by De Rujula2, is to study the shape, near the upper end-point of the internal bremsstrahlung spectrum in electron-capture β decay. The best nucleus for a precise measurement seems to be 163Ho, for which we have determined3 the Q EC value to be 2.83±0.05 keV. A particularly interesting possibility is to use total absorption spectrometry4 (calorimetry), in which the radioactive holmium forms part of the sensitive volume of the detector. With 5–6-MeV α particles impinging on the diamond wafer of the bolometer, a full-width-at-half-maximum (FWHM) of 36 keV was obtained at a temperature of 1.3 K. The theoretical resolution at 100 mK is a few electron-volts, so this new detection technique should give greatly enhanced energy resolution compared with present solid-state conductors based on charge carrier collection.
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| 2. |
- Stroke, H. H., et al.
(författare)
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Bolometers as Particle Spectrometers
- 1986
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Ingår i: IEEE Transactions on Nuclear Science. - 0018-9499. ; 33:1, s. 759-761
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Tidskriftsartikel (refereegranskat)
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| 3. |
- Bjornstad, T., et al.
(författare)
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Study of the Giant Gamow-Teller Resonance in Nuclear Beta-Decay - the Case of Ar-32
- 1985
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Ingår i: Nuclear Physics A. - : Elsevier BV. - 0375-9474. ; 443:2, s. 283-301
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Tidskriftsartikel (refereegranskat)abstract
- Delayed proton and gamma emissions following the β-decay of 32Ar have been studied. The half-life of 32Ar is 98 ± 2 ms, and the T = 2 analogue state in 32Cl lies at the excitation energy 5036 ± 12 keV. From the intensity of the feeding to this state the proton intensities can be converted to an absolute scale leading to a total proton branching ratio of (43 ± 3)%. From proton-gamma coincidence measurements it emerges that (1.9 ± 0.2)% of the protons lead to the first-excited state in 31S. A level scheme up to 8.75 MeV excitation in 32Cl has been constructed and the Gamow-Teller strength function has been deduced. The result is a renormalization of the axial-vector strength to (49 ± 5)% of the free-nucleon value.
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| 4. |
- Axelsson, H., et al.
(författare)
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Candidates for Electron-Neutrino Mass Measurements - the Case of Kr-81
- 1988
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Ingår i: Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics. - : Elsevier BV. - 0370-2693. ; 210:1-2, s. 249-252
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Tidskriftsartikel (refereegranskat)abstract
- The nuclear data of the known candidates for neutrino mass determination by resonant electron-capture beta decay are reviewed. New results are presented for the isotope 81Kr, where the transition to the 276 keV state has been found to have QEC=4.7±0.5 keV and a branching ratio of (3.0±0.2)×10−3
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| 5. |
- Bjornstad, T., et al.
(författare)
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The Doubly Closed Shell Nucleus Sn-132(50)82
- 1986
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Ingår i: Nuclear Physics A. - : Elsevier BV. - 0375-9474. ; 453:3, s. 463-485
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Tidskriftsartikel (refereegranskat)abstract
- The structure of excited states in 132Sn, fed in the β-decay of 132In, has been investigated. Absolute intensities were deduced from γ-singles measurements. From multi-spectrum analysis of γ-lines the half-life of 132In was determined to be 186 ± 22 ms. A level scheme based on γγ and βγ coincidences is presented. The conversion electron spectrum has been studied and internal conversion coefficients deduced for two low-energy transitions. The total decay energy of 132In was determined, from γ-gated β-spectra, to be Qβ = 13.6 ± 0.4 MeV. A lower limit of 6.968 MeV for the neutron separation energy in 132Sn was deduced from the β-delayed neutron spectrum. The experimental results on the level structure of the doubly closed shell nucleus 132Sn show that the shell model is applicable even far from the valley of stability.
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| 6. |
- Borchert, G. L., et al.
(författare)
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Mechanisms for K X-Ray-Energy Shifts
- 1987
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Ingår i: Zeitschrift für Naturforschung - Section A Journal of Physical Sciences. - 0932-0784. ; 42:8, s. 781-785
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Tidskriftsartikel (refereegranskat)
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| 7. |
- Borge, M. J. G., et al.
(författare)
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Limits on Neutrino-Mixing from the Internal Bremsstrahlung Spectrum of I-125
- 1986
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Ingår i: Physica Scripta. - 1402-4896 .- 0031-8949. ; 34:6A, s. 591-596
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Tidskriftsartikel (refereegranskat)abstract
- The massive antineutrino recently reported by Simpson in an experiment on tritium decay has not been confirmed by experiments on 35S decay. As an independent check, we report here the negative result of a search for the corresponding antiparticle (a massive neutrino) using the decay of 125I. As a by-product, we give accurate data on internal-bremsstrahlung spectra which we have followed over close to four decades in intensity, and we report a new way of measuring its E1/M1 ratio. The experiment provides a new and very accurate value for the 125I-125Te mass difference of 186.1 ± 0.3 keV.
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| 8. |
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| 9. |
- Riisager, K., et al.
(författare)
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The Internal Bremsstrahlung Spectra from the Ec Beta-Decay of Pt-193 and Ho-163
- 1985
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Ingår i: Physica Scripta. - : IOP Publishing. - 1402-4896 .- 0031-8949. ; 31:5, s. 321-327
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Tidskriftsartikel (refereegranskat)abstract
- Internal bremsstrahlung spectra following electron-capture (EC) beta decay have been calculated in two versions of an extended Glauber-Martin theory. The case of 193Pt which has a QEC-value that falls 20 keV below the 1s resonance point, is ideally suited for a test of this theory. The experimental data, both singles and L X-ray-bremsstrahlung coincidences, show that all the main features of the spectra are understood, although the absolute intensities agree to within a factor 1.5-2 only. The same calculations have been applied to 163Ho, with a QEC of 2.82 keV, one of the main cases for an accurate measurement of the electron neutrino mass. The predicted occurence of an interference minimum near the end-point, however, makes the m(ve) experiment less attractive than one might have hoped for.
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