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Experimental Particle and Astro-Particle Physics Seminar

Monday 14:00

UZH Irchel Y16 G05

Note: these seminars will continue remotely via Zoom after Easter, due to the ongoing restrictions in place as part of the Covid-19 response. Connection details will be made available.

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Current Program - Spring 2020



29 January


Y27 H 37

(note unusual time and location)

Yasmine Amhis

(Centre National de la Recherche Scientifique)

About the universality (or not) of loop induced beauty decays. 


The coupling of the electroweak gauge bosons of the Standard Model  to leptons is lepton flavour universal. Extensions of the Standard model do not necessarily have this property. Rare decays of heavy flavour are heavily suppressed in the Standard Model and new particles can give sizeable contributions to these processes, thus their precise study allows for sensitive tests of lepton flavour universality. Of particular interest are rare b->sll decays that are readily accessible at the LHCb experiment. Recent results from LHCb on lepton flavour universality in rare b->sll decays are discussed.

  Dr. Yuta Takahashi

17 February




24 February




2 March




9 March

Ashley Parker (University of Buffalo)

Differential Jet Production Cross Section Measurements at CMS


I begin with the motivation for studying jet mass in terms of understanding pQCD and decreasing uncertainties on future searches for new physics. I will then discuss our CMS dijet mass measurement as an introduction to my thesis research, the jet mass and dimensionless mass measurement with respect to transverse momentum in Z + jet events from the entire run 2 dataset of CMS.

  F. Canelli

16 March




23 March




30 March




6 April




13 April


Easter Monday


20 April




27 April

Dr. Patricia Sanchez (UZH)

Sensitivity of the DARWIN observatory to the neutrinoless double beta decay of 136-Xe


The DARWIN observatory is a proposed next-generation experiment to search for particle dark matter and for the neutrinoless double beta decay of 136-Xe. It will operate 40t of natural xenon in a time projection chamber, thus containing about 3.6t of 136-Xe. Here, we show that its projected half-life sensitivity is 2.4×1027yr, using a fiducial volume of 5t of natural xenon and 10 yr of operation with a background rate of less than 0.2  events/(t⋅⋅yr) in the energy region of interest. This sensitivity is based on a detailed Monte Carlo simulation study of the background and event topologies in the large, homogeneous target. DARWIN will be comparable in its science reach to dedicated double beta decay experiments using xenon enriched in 136-Xe.

Slides (PDF, 14 MB) Laura Baudis

4 May




11 May

Dr. R. Daniel Parsons (Humboldt University, Berlin)

Pulsars, Jets & GRBs: Recent Highlights from the H.E.S.S. Gamma-ray Observatory


In the 15 years since its construction, the H.E.S.S. gamma-ray observatory has allowed the study of the VHE gamma-ray sky at resolutions and sensitivities which were never before possible. During this period H.E.S.S. has discovered a rich zoo of both galactic and extra galactic source classes, made measurements of the galactic cosmic ray spectrum and placed limits on fundamental physical processes. 

I will present a brief summary of the some of the highlights of the H.E.S.S. observational programme, concentrating on the study of transient sources which has been a strong focus of the H.E.S.S. telescopes in recent years. Most notably this lead to the detection of two gamma-ray bursts in the very high energy range, but also has placed limits on the gamma-ray emission for the numerous gravitational wave sources (including GW 170817), Fast Radio Bursts and neutrino source candidates. Finally I will detail the latest upgrades to H.E.S.S. and the plans for future operation. 

slides (PDF, 16 MB) Alison Mitchell

18 May

Christian Wittweg (Uni Münster)

Rare, slow and special - Detecting the double-beta decays of Xe-124

The isotope 124Xe is exceedingly rare and long-lived. Still, its slow double-beta decays could be a key to understanding the mass and nature of the neutrino as well as the dominance of matter over antimatter in the Universe. What makes 124Xe special among double-beta emitters is the theoretical possibility of three different neutrinoless decay modes – either in a nuclear resonance, or involving the emission of one or two positrons. Together with the observation of neutrinoless double-beta decays in other isotopes, 124Xe could also allow to disentangle the underlying decay mechanism. The talk will introduce the neutrinoless and two-neutrino decays of 124Xe and discuss the detection prospects with upcoming experiments such as XENONnT, nEXO and DARWIN.

  Laura Baudis

25 May


Dr. Vagelis Gkougkousis

Low Gain Avalanche Diodes – Towards picosecond fast radiation hard fully segmented tracking?

The factor of 10 increase in LHC-Phase 2 instantaneous luminosity, results in a high multiplicity environment were vertex separation by means of position sensitive tracking becomes challenging. Addition of a < 60 psec timing layer, based on Low Gain Avalanche Diode technology, has been proposed by both CMS and ATLAS experiments in problematic regions to recover performance. By means of moderate intrinsic gain (~10), fast signals with high S/N are produced, providing a low-jitter and high charge approach. Main challenges include radiation hardness to fluences up to several times 1015 neq/cm2, fine segmentation, increased geometric acceptance and stability – efficiency in a continuous operation environment. The state of the art is presented in all fronts and future research directions are discussed. Gallium and Carbon implants are explored for radiation resistance enhancement in combination with trenches and non-segmented gain layers towards a fill factor increase.  

Link to slides Stefanos Leontsinis
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