Current dates

42. Week 2019


Monday, 10.14.

Special Seminar

Time, Place:

14:15 ,Central Seminar Room, Library building

Speaker:

Neil McFadden, University of New Mexico

Title:

Liquid Argon Optical Simulations and Xenon Doping R&D for LEGEND

Neutrinoless double beta decay is a hypothesized lepton-number-violating process in which two neutrons decay to two protons, producing two electrons but no electron anti-neutrinos. The LEGEND collaboration will search for this decay using high purity germanium detectors enriched in 76Ge with the sensitiv- ity goal of half-lives in excess of 1028 yr. A staged approach is being proposed in which a 200 kg 76Ge detector array will be instrumented, followed by a phase-II at a tonne scale (L-1000). To increase the light collection efficiency of the L-200 liquid argon veto, several possible germanium detector array geometries are being explored using simulated optical probability maps. These maps, created with Geant4, are used to calculate photon detection probability as a function of position. This map is cross checked against a full Geant4 optical simulation and shown to be consistent. To validate this simulation technique against physical measurements, an optical map has been created for a 105 litre liquid argon test vessel dubbed BACoN. This map is used to predict the light yield from cos- mic muons and a 60Co source with the goal of demonstrating that the optical properties are implemented correctly.For L-1000, an even lower background index is desired. To reach this goal, xenon doped argon is being investigated. By adding 10-100 ppm of xenon to argon, the scintillation light of argon is shifted from 128 nm to 175 nm. Argon is transparent at 175 nm and materials are more reflective at 175 nm. Thus xenon-doped argon yields more light than pure argon and increases the veto power of the active shield. Based on the physical properties of xenon doped argon measured in this test stand, an optical map of L-1000 containing xenon doped argon will be created. This map can then be used to predict the increases veto power of xenon doping for L-1000.

Particle and Astroparticle Theory Seminar

Time, Place:

16:30 ,Seminar room Lindner 339, Gentner lab, 2nd floor

Speaker:

Dr. Shao-Feng Ge

Title:

Why should nature choose the normal mass hierarchy

Tuesday, 10.15.

Betriebsversammlung

Time, Place:

10:00 ,Otto-Hahn-Hörsaal

Speaker:

Betriebsrat

Astrophysics Seminar

Time, Place:

14:00 ,Central seminar room, library building

Speaker:

Dr. Damien Bégué, MPE Garching

Title:

The problematic connection between gamma-ray bursts and ultra-high energy cosmic rays

Abstract:The acceleration site for ultra-high energy cosmic rays (UHECR) is still an open question despite extended research and gamma-ray bursts (GRBs) are considered one of the most promising source candidates. Under the likely assumption that electrons are also accelerated at the UHECR acceleration site, synchrotron emission from these co-accelerated electrons is inevitable. We characterize this synchrotron emission and compare it to observed GRB spectra and find that for standard parameters, the synchrotron flux from these electrons would be much too luminous. This result challenges both high- and low-luminosity GRBs as accelerators of UHECR. A detailed discussion on GRB 060218 as UHECR source is also presented.

Thursday, 10.17.

Teekolloquium

Time, Place:

11:15 ,Grosser Hoersaal/Big Lecture Hall (library)

Speaker:

Prof. Oriol Vendrell Romagosa, Heidelberg University

Title:

Correlated quantum dynamics of nuclei, electrons and photons

Friday, 10.18.

Special Seminar

Time, Place:

11:00 ,Central Seminar Room, Library building

Speaker:

Grigorios Katsoulakos, MPIK

Title:

Nonthermal Processes Near Supermassive Black Holes

In recent years, gamma-ray astronomy has made considerable progress in the exploration of the extragalactic gamma-ray sky. In particular, active galaxies, whose relativistic jets/outflows are significantly inclined with respect to the line-of-sight, have revealed remarkable flaring activity at gamma-ray energies. The observed rapid variability of the gamma-ray emission, comparable to timescales of the light travel time across the black hole horizon, provides a strong motivation for testing radiative scenarios associated with the vicinity of the central supermassive black hole. In this study, we explore the so-called black hole magnetospheric scenario. Accordingly, strong particle acceleration may occur within the black hole magnetosphere in regions of unscreened electric fields (gaps). This can happen either at the null surface across which the charge density changes sign or at the stagnation surface which separates the inwardly from the outwardly moving matter. The acceleration of leptons is accompanied by gamma-ray emission via inverse Compton scattering of the ambient (disk) soft photons as well as curvature radiation. This study explores the potential of these processes to account for the observed gamma-ray features. By developing and studying an one-dimensional, steady model for magnetospheric particle acceleration and emission, as well as, estimating the terminal Lorentz factors of the accelerated charges and the maximum extractable gap power, we find that magnetospheric processes can be responsible for the observed, rapidly variable very-high-energy gamma-ray emission in the radio galaxy M87.

Special Seminar

Time, Place:

11:00 ,Seminar room Lindner 339, Gentner lab, 2nd floor

Speaker:

Stéphane Lucas, University of Namur

Title:

Plasma deposition in a Nuclear Lab: a journey from plasma reactor to functional structural material via monte-carlo simulation of film growth and nuclear reactions for composition analysis

43. Week 2019


Monday, 10.21.

Particle and Astroparticle Theory Seminar

Time, Place:

16:30 ,Central Seminar Room Library Building

Speaker:

Dr. Adrià Gómez-Valent (U. Heidelberg, ITP)

Title:

The Hubble Crisis

Joint Seminar with ITP Heidelberg

Tuesday, 10.22.

Seminar Theoretische Quantendynamik

Time, Place:

11:15 ,Seminarraum 242, Bothe-Labor

Speaker:

Dr. Pavlo Bilous, MPIK

Title:

Energy of the Th-229 nuclear clock transition

Wednesday, 10.23.

Bothe-Kolloquium

Time, Place:

11:15 ,Central seminar room, library building

Speaker:

Prof. Walter Pfeiffer, University of Bielefeld

Title:

tba