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542 results on '"Vermeeren, L."'

201. β-decay study of54,55Niproduced by an element-selective laser ion source

Author

Reusen, I., primary, Andreyev, A., additional, Andrzejewski, J., additional, Bijnens, N., additional, Franchoo, S., additional, Huyse, M., additional, Kudryavtsev, Yu., additional, Kruglov, K., additional, Mueller, W. F., additional, Piechaczek, A., additional, Raabe, R., additional, Rykaczewski, K., additional, Szerypo, J., additional, Van Duppen, P., additional, Vermeeren, L., additional, Wauters, J., additional, and Wöhr, A., additional

Published
1999
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202. β decay of67Co

Author

Weissman, L., primary, Andreyev, A., additional, Bruyneel, B., additional, Franchoo, S., additional, Huyse, M., additional, Kruglov, K., additional, Kudryavtsev, Y., additional, Mueller, W. F., additional, Raabe, R., additional, Reusen, I., additional, Van Duppen, P., additional, Van Roosbroeck, J., additional, Vermeeren, L., additional, Köster, U., additional, Kratz, K. L., additional, Pfeiffer, B., additional, Thirolf, P., additional, and Walters, W. B., additional

Published
1999
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203. Beta decay of neutron-rich Co: Probing single-particle states at and above the N=40 subshell closure

Author

Mueller, W. F., primary, Bruyneel, B., additional, Franchoo, S., additional, Huyse, M., additional, Köster, U., additional, Kratz, K.-L., additional, Kruglov, K., additional, Kudryavtsev, Y., additional, Pfeiffer, B., additional, Raabe, R., additional, Reusen, I., additional, Thirolf, P., additional, Van Duppen, P., additional, Van Roosbroeck, J., additional, Vermeeren, L., additional, Walters, W. B., additional, Weissman, L., additional, and Wöhr, A., additional

Published
1999
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205. In-beam Nuclear-polarization By Ion-beam Surface Interaction

Author

UCL - Autre, Vanderpoorten, W., Demoor, P., Schuurmans, P., Siebelink, R., Vancraeyest, G., Vanhaverbeke, J., Vermeeren, L., Vanneste, L., Wouters, Johan, Severijns, N., Vervier, Jean, Goldring, G., Silverans, R., UCL - Autre, Vanderpoorten, W., Demoor, P., Schuurmans, P., Siebelink, R., Vancraeyest, G., Vanhaverbeke, J., Vermeeren, L., Vanneste, L., Wouters, Johan, Severijns, N., Vervier, Jean, Goldring, G., and Silverans, R.

Abstract

Recently, a set-up to polarize nuclei 'in flight' has been developed at the LISOL isotope separator in Louvain-laNeuve. It is constructed in such a way that two complementary methods can be used: Tilted Foil (TF) and Ion Beam Surface Interaction at Grazing Incidence (IBSIGI). Both methods rely on an atomic polarization transfer to the nucleus, via hyperfine interaction. The atomic polarization is obstained by an anisotropic ion beam-surface interaction. This development completes the already existing Low Temperature Nuclear Orientation set-up and expands considerably the possibilities to polarize short lived nuclei. In a first run atomic polarizations of 50 keV N-14-beams were observed. Values up to 10% were obtained.

Published
1991

206. Beta Decay of68–74Niand Level Structure of Neutron-Rich Cu Isotopes

Author

Franchoo, S., primary, Huyse, M., additional, Kruglov, K., additional, Kudryavtsev, Y., additional, Mueller, W. F., additional, Raabe, R., additional, Reusen, I., additional, Van Duppen, P., additional, Van Roosbroeck, J., additional, Vermeeren, L., additional, Wöhr, A., additional, Kratz, K.-L., additional, Pfeiffer, B., additional, and Walters, W. B., additional

Published
1998
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207. Gamow-Teller strength in the

Author

Reusen, I., primary, Andreyev, A., additional, Andrzejewski, J., additional, Bijnens, N., additional, Bruyneel, B., additional, Franchoo, S., additional, Huyse, M., additional, Kudryavtsev, Y. A., additional, Kruglov, K., additional, Mueller, W. F., additional, Piechaczek, A., additional, Raabe, R., additional, Rykaczewski, K., additional, Szerypo, J., additional, Van Duppen, P., additional, Van Roosbroeck, J., additional, Vermeeren, L., additional, Wauters, J., additional, Weissman, L., additional, and Wöhr, A., additional

Published
1998
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208. Experiments with stored relativistic exotic nuclei

Author

Geissel, H., primary, Radon, T., additional, Attallah, F., additional, Beckert, K., additional, Bosch, F., additional, Dolinskiy, A., additional, Eickhoff, H., additional, Falch, M., additional, Franczak, B., additional, Franzke, B., additional, Fujita, Y., additional, Hausmann, M., additional, Hellström, M., additional, Herfurth, F., additional, Kerscher, Th., additional, Klepper, O., additional, Kluge, H.-J., additional, Kozhuharov, C., additional, Löbner, K. E. G., additional, Münzenberg, G., additional, Nolden, F., additional, Novikov, Yu., additional, Patyk, Z., additional, Quint, W., additional, Reich, H., additional, Scheidenberger, C., additional, Schlitt, B., additional, Stadlmann, J., additional, Steck, M., additional, Sümmerer, K., additional, Vermeeren, L., additional, Winkler, M., additional, Winkler, Th., additional, and Wollnik, H., additional

Published
1998
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209. Measurement of the magnetic moments of

Author

Kappertz, S., primary, Geithner, W., additional, Katko, G., additional, Keim, M., additional, Kotrotsios, G., additional, Lievens, P., additional, Neugart, R., additional, Vermeeren, L., additional, and Wilbert, S., additional

Published
1998
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210. Beta decay of neutron-rich cobalt and nickel isotopes

Author

Franchoo, S., primary, Bruyneel, B., additional, Huyse, M., additional, Köster, U., additional, Kratz, K.-L., additional, Kruglov, K., additional, Kudryavtsev, Y., additional, Mueller, W. F., additional, Pfeiffer, B., additional, Raabe, R., additional, Reusen, I., additional, Thirolf, P., additional, Van Duppen, P., additional, Van Roosbroeck, J., additional, Vermeeren, L., additional, Walters, W. B., additional, Weissman, L., additional, and Wöhr, A., additional

Published
1998
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211. A radio frequency quadrupole ion beam buncher for ISOLTRAP

Author

Bollen, G., primary, Dilling, J., additional, Dezfuli, A. M. Ghalambor, additional, Henry, S., additional, Herfurth, F., additional, Kellerbauer, A., additional, Kim, T., additional, Kluge, H.-J., additional, Kohl, A., additional, Lamour, E., additional, Lunney, D., additional, Moore, R. B., additional, Quint, W., additional, Schwarz, S., additional, Varfalvy, P., additional, and Vermeeren, L., additional

Published
1998
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212. β-NMR measurement of the nuclear quadrupole moments of

Author

Wilbert, S., primary, Brown, B. A., additional, Geithner, W., additional, Georg, U., additional, Kappertz, S., additional, Keim, M., additional, Lievens, P., additional, Neugart, R., additional, Neuroth, M., additional, and Vermeeren, L., additional

Published
1998
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216. Laser ion source for the Leuven Isotope Separator On‐Line

Author

Kudryavtsev, Yu. A., primary, Andrzejewski, J., additional, Bijnens, N., additional, Franchoo, S., additional, Huyse, M., additional, Piechaczek, A., additional, Szerypo, J., additional, Reusen, I., additional, Van Duppen, P., additional, Vermeeren, L., additional, Wauters, J., additional, and Wöhr, A., additional

Published
1996
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221. Beta decay of the new isotope101Sn

Author

Janas, Z, primary, Keller, H, additional, Kirchner, R, additional, Klepper, O, additional, Piechaczek, A, additional, Roeckl, E, additional, Schmid, K, additional, Huyse, M, additional, Schwarzenberg, J von, additional, Szerypo, J, additional, Duppen, P van, additional, Vermeeren, L, additional, Albus, F, additional, Kluge, H -J, additional, Passler, G, additional, Scheerer, F P, additional, Trautmann, N, additional, Fedoseyev, V N, additional, Mishin, V I, additional, Grzwacz, R, additional, Plochocki, A, additional, Rykaczewski, K, additional, and Zylicz, J, additional

Published
1995
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225. Beta decay of neutron-rich cobalt and nickel isotopes.

Author

Franchoo, S., Bruyneel, B., Huyse, M., Köster, U., Kratz, K.-L., Kruglov, K., Kudryavtsev, Y., Mueller, W. F., Pfeiffer, B., Raabe, R., Reusen, I., Thirolf, P., Van Duppen, P., Van Roosbroeck, J., Vermeeren, L., Walters, W. B., Weissman, L., and Wöhr, A.

Published
1998
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235. In-beam nuclear polarization by ion beam-surface interaction

Author

Vanderpoorten, W, primary, De Moor, P, additional, Schuurmans, P, additional, Siebelink, R, additional, Vancraeyest, G, additional, Vanhaverbeke, J, additional, Vermeeren, L, additional, Vanneste, L, additional, Wouters, J, additional, Severijns, N, additional, Vervier, J, additional, Goldring, G, additional, and Silverans, R, additional

Published
1991
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239. Experimental study of radiation induced electromotive force effects on mineral insulated cables.

Author

Nieuwenhove, R. Van and Vermeeren, L.

Subjects
*ELECTRIC potential, *RADIATION, *NUCLEAR activation analysis, *CABLES
Abstract

Measurements of radiation induced electromotive force (RIEMF) effects on mineral insulated cables in a pure gamma field and in a combined neutron and gamma field are presented and compared to model calculations. The effect of materials in the immediate surroundings of the cable, as predicted by the model calculations, is clearly demonstrated. In a fission reactor environment, delayed current contributions due to the neutron activation and subsequent beta emission in base materials as well as in impurities such as Mn are clearly observed and are well reproduced by model calculations. The prediction of the gamma induced current component was severely complicated by its strong sensitivity to the detailed geometry and the spectrum and the directivity of the gamma field. Although the RIEMF effect on MI cables can therefore in general not be completely eliminated, some guidelines are provided to minimize them. © 2003 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Published
2003
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240. Measurement of the electric quadrupole moments of 26–29Na.

Author

Keim, M., Georg, U., Klein, A., Neugart, R., Neuroth, M., Wilbert, S., Lievens, P., Vermeeren, L., and Brown, B.

Abstract

The nuclear electric quadrupole moments of the isotopes 26Na, 27Na, 28Na and 29Na were measured by β-NMR spectroscopy in single crystals of LiNbO3 and NaNO3. High degrees of nuclear polarization were produced by optical pumping of the sodium atoms in a fast beam with a collinear laser beam. The polarized nuclei were implanted into the crystals and NMR signals were observed in the β-decay asymmetries. Preparatory measurements also yielded improved values for the magnetic moments of 27–31Na and confirmed the spin I = 3/2 for 31Na. The results are discussed in comparison with large-basis shell model calculations. [ABSTRACT FROM AUTHOR]

Published
2000
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241. Preface.

Author

Lyoussi, A., Giot, M., Carette, M., Jenčič, I., Reynard-Carette, C., Vermeeren, L., Snoj, L., Le Dû, P., and Lyoussi, Abdallah

Subjects
RADIOACTIVE waste management, NUCLEAR physics, SOFTWARE engineering
Published
2020
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242. Hyperfine structure constants of the CaII states 4 s S and 4 p P and the nuclear quadrupole moment ofCa.

Author

Silverans, R., Vermeeren, L., Neugart, R., and Lievens, P.

Abstract

The hyperfine structure splittings of the 4 s S → 4 p P transitions inCaII have been measured by fast ion beam collinear laser spectroscopy. The resonant laser interaction was observed using non-optical detection based on optical ground state depopulation pumping, state selective neutralization and charge state separated particle counting. The extracted magnetic dipole hyperfine structure constants forCa A( S)=−805(2) MHz, A( P)=−145.5(1.0) MHz and A( P)=−31.9(0.2) MHz are in excellent agreement with relativistic many body perturbation theory predictions available for this alkali-like ion. The combined results are used to evaluate the semi-empirical analysis method. From the electrical quadrupole hyperfine structure constant B( P)=−6.7(1.4) MHz and the calculated B/Q value for this one valence electron configuration, the nuclear quadrupole moment Q(Ca)=−0.043(9) b is derived. This result supports a previous evaluation based on the hyperfine structure of the two valence electron P configurations of CaI. [ABSTRACT FROM AUTHOR]

Published
1991
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243. Schottky Mass Measurements of Cooled Exotic Nuclei

Author

Litvinov, Yu., Attallah, F., Beckert, K., Bosch, F., Falch, M., Franzke, B., Geissel, H., Hausmann, M., Kerscher, Th., Klepper, O., Kluge, H.-J., Kozhuharov, C., Löbner, K., Münzenberg, G., Nolden, F., Novikov, Yu., Patyk, Z., Quint, W., Radon, T., Scheidenberger, C., Steck, M., Vermeeren, L., and Wollnik, H.

Abstract

Projectile fragments of a 209Bi beam were separated in flight with the fragment separator FRS and injected into the experimental storage ring ESR. In the ESR a beam containing up to about 100 different isotopes was cooled to a relative velocity spread of δv/v=10−6by means of the electron cooler. The image currents of the ions induced in a Schottky pick-up probe at each turn were recorded. A subsequent Fast Fourier Transformation of these signals yields the revolution frequencies of the different isotopes stored in the ESR. Unknown masses of more than 150 neutron-deficient nuclides in the element range of 52≤Z≤85 have been measured directly by Schottky Mass Spectrometry and in addition more than 60 new masses have been obtained from α-decay chains. These new mass data allow the location of the one-proton dripline and the prediction of the two-proton dripline for heavy nuclides. The experimental masses are compared with different theoretical predictions.

Published
2001
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244. Measurement of nuclear moments and radii by collinear laser spectroscopy and by β-NMR spectroscopy

Author

Geithner, W., Georg, U., Kappertz, S., Keim, M., Klein, A., Lievens, P., Neugart, R., Neuroth, M., Vermeeren, L., and Wilbert, S.

Abstract

Experiments using laser spectroscopy and nuclear magnetic resonance techniques have been performed at ISOLDE on the unstable isotopes of several light elements. The results include nuclear ground state spins, magnetic dipole and electric quadrupole moments, and the behaviour of mean square nuclear charge radii within isotopic strings. These give important information about the nuclear structure at shell closures and close to the drip lines.

Published
2000
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245. Mass measurements of relativistic projectile fragments in the storage ring ESR

Author

Radon, T, Geissel, H, Attallah, F, Beckert, K, Bosch, F, Dolinskiy, A, Eickhoff, H, Falch, M, Franczak, B, Franzke, B, Fujita, Y, Hausmann, M, Hellström, M, Herfurth, F, Kerscher, Th, Klepper, O, Kluge, H-J, Kozhuharov, C, Litvinov, Yu, Löbner, KEG, Münzenberg, G, Nolden, F, Novikov, Yu, Patyk, Z, Quint, W, Reich, H, Scheidenberger, C, Schlitt, B, Stadlmann, J, Steck, M, Sümmerer, K, Vermeeren, L, Winkler, M, Winkler, Th, and Wollnik, H

Abstract

Two experimental methods of measuring masses of exotic nuclei in the storage ring ESR are presented. Bismuth and nickel fragments were produced via projectile fragmentation, separated and investigated with the combination of the fragment separator FRS and the ESR: (i) Direct mass measurements of relativistic projectile fragments were performed using Schottky mass spectrometry (SMS), i.e., exotic nuclei were stored and cooled in the ESR. Applying electron cooling, the relative velocity spread of circulating low intensity beams can be reduced below 10−6. Under this condition a mass resolving power of up to m/Δm=6.5·105(FWHM) was achieved in a recent measurement. Previously unknown masses of more than 100 neutron-deficient isotopes have been measured in the range of 60≤Z≤84. Using known Qαvalues the area of known masses could be extended to more exotic nuclei and to higher proton numbers. The results are compared with mass models and extrapolations of experimental values. In a second experiment with 209Bi projectiles the area of the measured masses was extended to lower proton numbers. Due to various improvements at the ESR the precision of the measurements could be raised. (ii) Exotic nuclei with half-lives shorter than the time needed for SMS (present limit: T1/2≈ 5 sec) can be investigated by time-of-flight measurements whereby the ESR is operated in the isochronous mode. This novel experimental technique has been successfully applied in first measurements with nickel and neon fragments where a mass resolving power of m/Δm=1.5·105(FWHM) was achieved.

Published
1999
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246. Sensitive laserspectroscopy on ions with hyperfine split transitions

Author

Vermeeren, L., Lievens, P., and Silverans, R.

Abstract

Abstract: Collinear laser—fast alkaline-earth ion beam interaction can be monitored sensitively by a detection sequence consisting of optical pumping to a metastable state, state-dependent neutralization, and separate counting of ions and atoms. Deceleration of the ions prior to neutralization strongly increases the sensitivity of the method. For ions with hyperfine split transitions the sensitivity can be considerably improved by a two-step optical pumping sequence. In this contribution, the results of rate equation calculations are compared to experimental results for Ba-and Sr-beams, including a shortlived99Sr beam of very low intensity.

Published
1990
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248. The electronic field shift factor of the 4s2S1/2−4p2PJ transitions in CaII

Author

Silverans, R. E., Vermeeren, L., Klein, A., Neugart, R., Schulz, C., and Lievens, P.

Abstract

The isotope shifts (IS) of the resonance lines 4s2S1/2-4p2PJin CaII (seven isotopes) have been measured by fast ion beam collinear laser spectroscopy (FIBCLS) with non-optical detection of the resonant laser-ion interaction. The electronic field shift factorF was derived from the experimental IS via a King plot procedure using the mean square nuclear charge radii from muon spectroscopy andelectron scattering. TheJ-independent resultF=-283(6) Mhz/fm2 was obtained. TheF-value resulting from extensive many body perturbation theory (MBPT) calculations, recently performed by Märtensson-Pendrill et al., is in excellent agreement with the experimental value, confirming the reliability of the MBPT procedure.

Published
1993
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250. Nuclear moments of strongly deformed strontium isotopes

Author

Lievens, P., Silverans, R., Vermeeren, L., Arnold, E., Borchers, W., Neu, W., Neugart, R., Wendt, K., Buchinger, F., Ramsey, E., and Ulm, G.

Abstract

Abstract: Nuclear spins, moments and mean square charge radii of78–100Sr have been obtained by fast ion-beam collinear laserspectroscopy. The experiments performed at ISOLDE have been extended to include99Sr, measured by a non-optical detection scheme with a two-step optical pumping sequence. The results for the strongly deformed isotopes are discussed in the frame of the particle-plus-deformed core model.

Published
1990
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