Josef Homolka

Technische Universität München | TUM · Lehrstuhl für Physik der Hadronen und Kerne (E12)

Der Geschäftsbetrieb einer Universität ist durch zunehmende Digitalisierung und Nutzung elektronischer Medien gekennzeichnet. Die Einführung immer leistungsfähigerer zentraler IT-Systeme führt zu einer komplexen Vielfalt heterogener Benutzer- und Administrationsschnittstellen. Zur Schaffung einer umfassenden benutzerfreundlichen und nahtlosen IT-In...

HADES is a versatile magnetic spectrometer aimed at studying dielectron production in pion, proton and heavy-ion-induced collisions. Its main features include a ring imaging gas Cherenkov detector for electron-hadron discrimination, a tracking system consisting of a set of 6 superconducting coils producing a toroidal field and drift chambers and a...

The High‐Acceptance Di‐Electron Spectrometer installed at GSI Darmstadt is a second generation experiment to study production of dielectron pairs from proton, pion and nucleus induced reactions at the SIS∕BEVALAC energy regime. During period 2002–4 medium‐resolution data have been taken with HADES on the light C+C system at 1 and 2 AGeV. The data a...

The invariant-mass spectrum of e+e- pairs produced in 12C+12C collisions at an incident energy of 2 GeV per nucleon has been measured for the first time. The measured pair production probabilities span over 5 orders of magnitude from the pi(0)-Dalitz to the rho/omega invariant-mass region. Dalitz decays of pi(0) and eta account for all the yield up...

We report the first observation of the doubly-magic nucleus 100Sn. This isotope was produced by nuclear fragmentation of 124Xe projectiles at 1095 A MeV using the heavy-ion synchrotron SIS at GSI, Darmstadt. The projectile fragments were separated in flight with the projectile fragment separator FRS and identified by measuring event by event magnet...

For the FAIR Project at Darmstadt an antiproton-ion collider has been proposed to independently determine rms radii for protons and neutrons in stable and short lived nuclei by means of antiproton absorption at medium energies. The experiment makes use of the electron ion collider complex to store, cool and collide antiprotons of 30 MeV energy with...

An antiproton-ion collider is proposed to independently determine rms radii for protons and neutrons instable and short lived nuclei by means of antiproton absorption at me-dium energies[1]. The experiment makes use of the electron ion collider complex[2] with appropriate modifications of the electron ring to store, cool and collide antiprotons of...

An antiproton-ion collider (AIC) has been proposed for the FAIR Project at Darmstadt to independently determine rms radii for protons and neutrons in stable and short lived nuclei by means of antiproton annihilation at medium energies. The AIC makes use of the ELISe electron ion collider complex to store, cool and collide antiprotons of 30 MeV ener...

The HADES RICH detector at GSI is equipped with a spherical mirror segments of 433mm focal length. The complete mirror consisting of six sectors has a diameter of 144 cm. The Al reflection layer was protected by a MgF2 film of the optimal thickness for best reflectivity in the wavelength range of 140 nm < 2 < 220 nm. Since the optical quality of th...

Electrons and positrons from pi0 decays have been measured for C+C collisions at 1AGeV beam energy. Reconstructed e+e--pairs from pi0-Dalitz decays have been used as a calibrated electron source for the investigation of Cherenkov rings detected in a hadron blind RICH with CsI-based photo cathode. The measured ring properties are in good agreement w...

We report the results of an experiment to measure the overall photon detection efficiency of the HADES RICH. Cherenkov radiation from light carbon ions was used to produce single photons in the accessible wavelength region between 145 and 220nm. The photon detector response to single photons is described by a parametrisation. The total light yield...

The setup in the UHV box coater for the HADES RICH mirrors was modified to deposit VUV reflective layers on large area substrates. These substrates were made of 2mm thick float glass with 87cm spherical curvature and a perimeter of 86cm. A good uniformity of the coatings could be obtained by a larger source-to-substrate distance of 155cm. Impurity...

A Ring Imaging CHerenkov detector is used in the HADES spectrometer to identify e+e− pairs from meson decays produced in hadron and heavy-ion induced collisions at a few A GeV incident energy. The full event pattern information of 28 272 pads has to be transferred within to an image processor, where the typical lepton rings have to be identified wi...

The performance of a 48 x 48 cm(2) multi-wire proportional chamber for VUV photon detection in a RICH setup is reported. The MWPC pad cathode was covered with a solid CsI photo converter layer of 230 mu g/cm(2) thickness deposited on a resin-stabilized graphite (RSG) coating. Cherenkov light radiated from cosmic muons was detected in the wavelength...

Quantum efficiencies (QE) in the vacuum ultraviolet (VUV) wavelength region have been measured for solid CsI layers on various substrates. The CsI films were deposited applying electron beam evaporation. The QE measurements were performed utilizing synchrotron radiation as well as light from a deuterium lamp. A GaAsP diode with a sensitivity calibr...

The readout electronics for the HADES RICH uses new concepts for the data transport and a multilevel trigger scheme for online data reduction. We have developed two types of modules for the readout of the RICH detector that is used for lepton identification in the HADES spectrometer. The first one is a mixed analog and digital frontend module that...

A fast RICH will act as a hadron blind trigger device in the high-resolution di-electron spectrometer HADES. The goal is to identify e+e− pairs from meson decays produced in hadron and heavy-ion induced collisions at a few GeV/nucleon incident energy. Concept and expected performance of the RICH utilizing a C4F10-radiator and a gaseous photon detec...

A novel technique for particle identification of relativistic heavy ions has been developed utilizing a Heavy-Ion Ring Imaging Cherenkov detector (HIRICH) for velocity measurement. The HIRICH is characterized by a thin liquid or solid state radiator, a proximity focusing geometry and a fast gaseous photon detector with CsI photon converter. A veloc...

A detector setup is presented which has been installed in the Experimental Storage (ESR) Ring at GSI (Darmstadt) for investigations of elastic and inelastic proton scattering on stored ion beams. Beams of various stable isotopes as well as - for the first time secondary Ni-56 nuclei provided by the Fragment Separator (FRS) have been accumulated and...

A detector setup is presented which has been installed in the Experimental Storage (ESR) Ring at GSI (Darmstadt) for investigations of elastic and inelastic proton scattering on stored ion beams. Beams of various stable isotopes as well as — for the first time — secondary 56Ni nuclei provided by the Fragment Separator (FRS) have been accumulated an...

We have identified the doubly-magic N = Z nucleus 100Sn by using the method of high-energy projectile fragmentation of a 124Xe beam in connection with the fragment separator FRS at GSI. Despite a very low production cross section of only 11 ± 4 pb, we report on first results from the investigation of correlated β-decays after the implantation of a...

The recoil detection method has been used to measure the differential cross sections at nucleon backward angles, 160°â180° (cm), for the {sup 12,13}C({ital p},{ital p}){sup 12,13}C and {sup 12,13}C({ital p},{ital n}){sup 12,13}N reactions at an incident proton energy of 200 MeV. These are the first reported data in this angular region. The elasti...

We report the performance of a VUV-sensitive MWPC with a pad cathode covered by a solid CsI photon converter. Cherenkov photons produced by relativistic 12C ions in a MgF2 radiator have been detected with 95% single photo electron efficiency. In the HADES design a resulting figure of merit N0 > 66 promises proper operation of the RICH as a fast had...

The production of energetic π− at 0° has been measured in Ne+NaF and Ni+Ni collisions with incident energies between 1.3 and 2AGeV. In Ne+NaF collisions the investigation was extended to extreme subthreshold processes with lab momenta up to 4.5 GeV/c. In both systems at all incident energies the π− production cross sections deviate in a systematic...

CsI photocathodes were studied in order to evaluate their potential use as large photoconverters in RICH detectors for the PID system at ALICE (LHC in heavy ion collider mode). It has been demonstrated that a quantum efficiency comparable to the reference value obtained on small samples can be obtained on CsI layers evaporated on large pad electrod...

We report here on the results obtained by the CERN RD26 collaboration on the production and characterization of large area photocathodes, susceptible to equip fast UV-photon imaging devices. Such detectors are planned for some Ring Imaging Cherenkov (RICH) detector projects, in particular HADES at SIS Darmstadt, BABAR at the SLAG asymmetric B-facto...

We report the first observation of the doubly-magic nucleus 100Sn. The isotope was produced by nuclear fragmentation of 124Xe projectiles at 1095 A·MeV using the heavy-ion synchrotron SIS at GSI Darmstadt. The projectile fragments were separated in flight with the projectile-fragment separator FRS and identified by measuring event by event the magn...

We report the first observation of the doubly-magic nucleus100Sn. This isotope was produced by nuclear fragmentation of124Xe projectiles at 1095 AMeV using the heavy-ion synchrotron SIS at GSI, Darmstadt. The projectile fragments were separated in flight with the projectile-fragment separator FRS and identified by measuring event by event the magne...

Subthreshold p andK – and energetic – production was studied in Ne + NaF, Cu, Sn and Bi, and in Ni + Ni collisions with incident energies between 1.6 and 2 GeV/u. The measured cross sections indicate a dominant contribution of baryonic resonances. This is also consistent with a generalized scaling behaviour of the cross sections with the energy ava...

We measured cross sections for the subthreshold production of antiprotons and K-mesons in nucleus-nucleus collisions for the systems Ne+NaF, Cu, Sn, and Bi, and recently also Ni+Ni, using Ne-20 and Ni-58 beams from the heavy ion synchrotron (SIS) at GSI with energies between 1.6 GeV/u and 2.0 GeV/u . Pi- production cross sections were also determin...

Differential cross sections for the neutral pion production reaction 12C(p,π0)13Ng.s. have been measured at 153.5, 166.1, 186.0, and 204.0 MeV bombarding energy using recoil detection. The shape of the angular distribution agrees well with that of the mirror reaction 12C(p,π+)13Cg.s.. Isospin invariance predicts for the ratio of the cross sections...

In fusion reactions of58Ni beams with54Pe and58Ni target nuclei neutron deficient evaporation residues have been produced and separated from the beam in an electrostatic deflector with large acceptance. The recoil nuclei were implanted and detected in an array of 100 PIN photodiodes, where also their particle decays were recorded. The assignment of...

The detection of neutral particles or exotic ejectiles in reactions initiated by medium energy probes is discussed. (AIP)

Cross sections for the reaction 12C(p,π0)13Ng.s. have been measured at 153.5, 166.1, 186.0 and 204.0 MeV bombarding energy by detection of the 13N recoil ions. The shapes of the differential cross section angular distributions agree well with those for the 12C(p,π+)13Cg.s. reaction obtained by pion detection. The ratio of the (p,π+) to (p,π0) total...

The pionic fusion reaction 12He,π+)15N has been measured at 170.2 and 236.3 MeV bombarding energy using recoil detection. At T3He=170.2 MeV the angle-integrated cross section for the population of both the 15Ng.s. and a broad group of unresolved 15N excited states between Ex=6 and 10 MeV is less than 0.03 nb. At T3He=236.3 MeV the total cross secti...

A method is described for studying reactions at medium energies by measuring the magnetic rigidity, time of flight, and energy loss of the resulting recoil products. The method works best for reactions with two-body final states where one of the outgoing particles is relatively light. A magnetic spectrometer with a special focal plane detector has...

Cross sections for the reaction ¹²C(p,Ï°)¹³N{sub {ital g}.{ital s}.} have been measured at 153.5, 166.1, 186.0 and 204.0 MeV bombarding energy by detection of the ¹³N recoil ions. The shapes of the differential cross section angular distributions agree well with those for the ¹²C(p,Ï{sup +})¹³C{sub {ital g}.{ital s}.} reaction obtained b...

The pionic fusion reaction ¹²C(³He,/pi//sup +/)¹⁵N has been measured at 170.2 and 236.3 MeV bombarding energy using recoil detection. At T/sub

This research was sponsored by the National Science Foundation Grant NSF PHY-9314783

This research was sponsored by the National Science Foundation Grant NSF PHY-9314783

This research was sponsored by the National Science Foundation Grant NSF PHY-9314783

This research was sponsored by the National Science Foundation Grant NSF PHY-9314783

This research was sponsored by the National Science Foundation Grant NSF PHY-9314783

This research was sponsored by the National Science Foundation Grant NSF PHY-9314783

This research was sponsored by the National Science Foundation Grant NSF PHY-9314783

This research was sponsored by the National Science Foundation Grant NSF PHY 87-14406

This research was sponsored by the National Science Foundation Grant NSF PHY 87-14406