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Dive into the research topics where Hans Wilschut is active.

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Featured researches published by Hans Wilschut.


European Physical Journal A | 1997

Production of pi(0) and eta mesons in carbon-induced relativistic heavy-ion collisions

Ralf Peter Averbeck; A Doppenschmidt; M. Appenheimer; Y. Charbonnier; J. Díaz; V. Hejny; S. Hlavac; R. Holzmann; A. Kugler; F. Lefèvre; H. Löhner; A Marin; V. Metag; W Niebur; R. Novotny; R.W. Ostendorf; R. Pleskac; A. Schubert; Y Schutz; Rudolf Siemssen; R.S. Simon; R. Stratmann; H. Ströher; P. Tlustý; P.H. Vogt; V. Wagner; J. Weiss; Hans Wilschut; F. Wissmann; A.R. Wolf

The production of π0 and η mesons has been investigated in the system 12C+12C at 0.8A GeV, 1.0A GeV, and 2.0A GeV using the TAPS photon detector. The production cross sections and transverse-momentum distributions measured around midrapidity extend the existing systematics of neutral-meson production to light systems and the highest energy available at the GSI accelerator facility. At all beam energies scaling of the differential production cross section with the transverse mass of the emitted meson is observed. In addition π0 production has been studied in the mass-asymmetric systems 12C+197Au and 197Au+12C at 0.8A GeV.


Physics Letters B | 1995

Bremsstrahlung photons as a probe of hot nuclei

G. Martínez; F.M. Marqués; Y. Schutz; G. Wolf; J. Diaz; M. Franke; S. Hlavac; R. Holzmann; P. Lautridou; F. Lefèvre; H. Löhner; A Marin; T. Matulewicz; W. Mittig; R.W. Ostendorf; J.H.G. van Pol; J. Québert; P. Roussel-Chomaz; A. Schubert; Rudolf Siemssen; R.S. Simon; Z. Sujkowski; V. Wagner; Hans Wilschut

Abstract Aside from the dominant production of hard photons in first-chance p-n collisions, a significant hard-photon production in a later stage of heavy-ion reactions is predicted by the BUU theory. These thermal hard photons are emitted from a nearly thermalized source and still originate from bremsstrahlung produced in individual p-n collisions. The calculations predict that the production of the thermal hard photons is strongly correlated with the incompressibility of nuclear matter. Tentative experimental evidence for their production is found in the hard-photon energy spectra measured in the systems 86 Kr + nat Ni at 60.0 A MeV, 181 Ta+ 197 Au at 39.5 MeV and 208 Pb+ 197 Au at 29.5 A MeV.


Physical Review C | 2003

Astrophysical rate of O-15(alpha,gamma)Ne-19 via the (p, t) reaction in inverse kinematics

B. Davids; van den Ad M Berg; Peter Dendooven; F. Fleurot; M. Hunyadi; Ma de Huu; Rudolf Siemssen; Hans Wilschut; H.J. Wörtche; Margarita Hernanz; Jordi Jose; K. E. Rehm; A. H. Wuosmaa; R. E. Segel

A recoil coincidence technique has been applied to measure the alpha-decay branching ratios of near-threshold states in Ne-19. Populating these states using the (p,t) reaction in inverse kinematics, we detected the recoils and their decay products with 100% geometric efficiency using a magnetic spectrometer. Combining our branching ratio measurements with independent determinations of the radiative widths of these states, we calculate the astrophysical rate of O-15(alpha,gamma)Ne-19. Using this reaction rate, we perform hydrodynamic calculations of nova outbursts and conclude that no significant breakout from the hot CNO cycles into the rp process occurs in novae via O-15(alpha,gamma)Ne-19.


Reviews of Modern Physics | 2015

Symmetry violations in nuclear and neutron

K. Keri Vos; Hans Wilschut; Robertus Timmermans

The role of beta decay as a low-energy probe of physics beyond the standard model is reviewed. Traditional searches for deviations from the standard model structure of the weak interaction in beta decay are discussed in light of constraints from the Large Hadron Collider and the neutrino mass. Limits on the violation of time-reversal symmetry in beta decay are compared to the strong constraints from electric dipole moments. Novel searches for Lorentz symmetry breaking in the weak interaction in beta decay are also included, where the unique sensitivity of beta decay to test Lorentz invariance is discussed. In the conclusion a possible road map for future beta-decay experiments is presented.


Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment | 2001

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R Bieber; van den Ad M Berg; K. Ermisch; V. Hannen; Mohsen Harakeh; H. Huisman; de Huu; N. Kalantar-Nayestanaki; Johannes Messchendorp; M. Seip; M. Volkerts; J. Volmer; S.Y. van der Werf; Hans Wilschut

A beam polarimeter for medium-energy protons and deuterons has been constructed. Its operation is based on the elastic-scattering reactions (p) over right arrow + p or (d) over right arrow + p. The outgoing particles are detected in kinematical coincidence in four independent reaction planes, each equipped with two pairs of phoswich detectors


Physics Letters B | 1995

decay

Fm Marques; G. Martínez; Y Schutz; J. Diaz; M Franke; S. Hlavac; R. Holzmann; P. Lautridou; F Lefevre; H. Löhner; A Marin; T. Matulewicz; W Mittig; R.W. Ostendorf; Jhg Vanpol; J. Québert; P. Roussel-Chomaz; A Schubert; Rudolf Siemssen; R.S. Simon; Z Sujkowski; Wagner; Hans Wilschut; G. Wolf

Abstract We have analyzed hard-photon intensity correlations measured in the systems 86 Kr+ nat Ni at 60.0 A MeV and 181 Ta+ 197 Au at 39.5 A MeV assuming that hard photons are emitted from two distinct sources in space-time. We confirm the existence of the Bose-Einstein correlation between independent hard photons and attribute the origin of the two sources to the density oscillations of nuclear matter generated in intermediate-energy heavy-ion collisions via the incomplete-fusion reaction mechanism.


Nuclear Physics | 1997

Performance of the KVI in-beam polarimeter

Y Schutz; G. Martínez; F.M. Marqués; A. Marín; T. Matulewicz; R.W. Ostendorf; P. Bożek; H. Delagrange; J. Díaz; M. Franke; K.K. Gudima; S Hlavac; R. Holzmann; P. Lautridou; F. Lefèvre; H. Löhner; W. Mittig; M. Płoszajczak; J.H.G. van Pol; J. Québert; P. Roussel-Chomaz; A. Schubert; Rudolf Siemssen; R.S. Simon; Z. Sujkowski; V. D. Toneev; V. Wagner; Hans Wilschut; G. Wolf

Abstract The dynamics of heavy-ion collisions is studied in an energy domain in the vicinity of the Fermi energy. The early history of the collision is analyzed from the theoretical and experimental point of view in which the message conveyed by bremsstrahlung photons and neutral pions is exploited. The Boltzmann-Uehling-Uhlenbeck model and the Dubna Cascade Model, both based on similar principles but each adopting different computation technics, are briefly described and their respective predictions are discussed. In particular the emission pattern of bremsstrahlung photons is discussed. The photon production has been measured in the systems 86 Kr+ 58 Ni at 60 A MeV, 181 Ta+ 197 Au at 40 A MeV and 208 Pb+ 197 Au at 30 A MeV and energy spectra, angular distributions and two-photon correlations have been analyzed. We find that bremsstrahlung photons are emitted from two distinct sources that can be correlated with nuclear-matter density oscillations. The properties of photon emission are discussed in terms of collective properties of nuclear matter. The high energy tail of the photon spectrum is interpreted by π 0 and Δ decay but predominantly by radiative capture of pions. The π 0 absorption in the nuclear medium is further analyzed by examining their emission pattern.


Physics Letters B | 1983

Density oscillations in systems of colliding heavy ions observed via hard-photon interferometry measurements☆

Hans Wilschut; Rk Bhowmik; Pb Goldhoorn; J.F.W. Jansen; Rudolf Siemssen; K. Siwek-Wilczyńska; Z. Sujkowski; J. Wilczyński

To identify the residual nuclei in very asymmetric heavy-ion reactions heavy-ion K X-ray coincidences have been measured. The usefulness and limitations of this method are discussed, and its feasibility is demonstrated in a study of the 14N+197Au reaction at 140 MeV.


Physics Letters B | 1994

Hard photons and neutral pions as probes of hot and dense nuclear matter

G. Martínez; J. Diaz; M. Franke; S. Hlavac; R. Holzmann; P. Lautridou; F Lefevre; H. Löhner; A Marin; M. Marqués; T. Matulewicz; W. Mittig; R.W. Ostendorf; J.H.G. van Pol; J. Québert; P. Roussel-Chomaz; Y. Schutz; A Schubert; Rudolf Siemssen; R.S. Simon; Z. Sujkowski; V. Wagner; Hans Wilschut

Abstract Hard photon production was investigated in the system 68 Kr+ nat Ni at 60 A MeV for a wide range of impact parameters. The parameters characteristic of hard photon emission such as source velocities, angular distributions and energy spectra were studied from peripheral to central collisions. The energy spectrum is seen to be strongly dependent on the centrality of the collision reflecting both a static and dynamic momentum distribution of the nucleons inside the collision zone.


Physical Review Letters | 2013

SELECTION OF HEAVY-ION REACTION CHANNELS VIA PARTICLE K X-RAY COINCIDENCES

J. P. Noordmans; Hans Wilschut; Robertus Timmermans

Forbidden (slow) β decays offer new opportunities to test the invariance of the weak interaction under Lorentz transformations. Within a general effective field theory framework we analyze and reinterpret the only two relevant experiments, performed in the 1970s, dedicated to search for a preferred direction in space in first- and second-forbidden β decays. We show that the results of these experiments put strong and unique limits on Lorentz violation, and in particular on the presence of several interactions in the modern Lorentz-violating standard model extension. We discuss prospects to improve on these limits.

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H. Löhner

University of Groningen

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R. Holzmann

Spanish National Research Council

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Y Schutz

Centre national de la recherche scientifique

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A Marin

Spanish National Research Council

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