Third MT student retreat

30 Jan 2017, 13:00 → 31 Jan 2017, 13:10 Europe/Berlin

KBW Hörsaal (GSI Darmstadt)

The third student retreat within the Helmholtz program "Matter and Technologies" is a meeting of PhD students to get to know each other and to exchange ideas and solutions. It will take place just before the third annual meeting of this Helmholtz program. We would like to start the day at 1 pm with scientific sessions dedicated to introductory or overview talks, where students may present their work to a “non-expert” audience. The goal is that the students get an impression which variety of fields of work constitutes the program “Matter and Technologies”. In the evening, we will organize a get-together. On the second day, we will have a discussion on issues which are important to PhD students in today’s perspective. Finally, we will get a GSI/FAIR tour.

Monday, 30 January

Welcome

Scientific Talks 1: The different topics PhD students are working on within Matter Technology

1 R&D status of the new superconducting CW heavy Ion LINAC@GSI

For future research in the field of Super Heavy Elements (SHE) a superconducting (sc) continuous wave (cw) ion LINAC with high intensity is highly desirable. Presently a multi-stage R&D program conducted by GSI, HIM and IAP is in progress. The fundamental linac design composes a high performance ion source, a new low energy beam transport line, the High Charge State Injector (HLI) upgraded for cw, and a matching line (1.4 MeV/u) followed by the new sc-DTL LINAC for acceleration up to 7.3 MeV/u. The successful commissioning of the first Crossbar-H-mode (CH) cavity (Demonstrator), in a vertical cryo module, was a major milestone in 2015. The next stage of the new sc cw heavy ion LINAC is the advanced demonstrator comprising a string of cavities and focusing elements build from several short constant-beta sc CH-cavities operated at 217 MHz. Currently the first two sc 8 gap CH-cavities are under construction at Research Instruments (RI), Bergisch Gladbach, Germany. The new design without girders and with stiffening brackets at the front and end cap potentially reduces the overall technical risks during the construction phase and the pressure sensitivity of the cavity. The recent status of the construction phase as well as an outlook for further cavity development of the new cw heavy ion LINAC will be presented.

Speaker: Mr Markus Basten (IAP University Frankfurt am Main)

2 Structural Mechanical Design Optimizations for a Newly Revised 4-Rod CW RFQ for the HLI

The High Charge State Injector (HLI) at the GSI Helmholtz Centre for Heavy Ion Research in Darmstadt, Germany, serves as one of the two injector linacs for the UNILAC as well as dedicated injector for the upcoming cw linac project for super heavy element research. As the front end of the HLI is planned to be upgraded for cw operation a newly revised cw capable RFQ structure with an operating frequency of 108 MHz is required. The existing 4-rod structure, which was commissioned at the HLI in 2010, suffers from severe modulated rf power reflections originating from mechanical oscillations of the electrodes that both limit the achievable performance and impede stable operation. Besides preceding vibration measurements that were done by GSI using a laser vibrometer, the structural mechanical behavior of the 4-rod geometry was extensively analyzed using ANSYS. Thereby the crucial mechanical eigenmodes could be identified and their impact on the rf properties was investigated by simulations using CST MWS. A completely newly revised 4-rod RFQ design with optimized structural rigidity was developed of which a 6-stem prototype is currently being manufactured.

Speaker: Mr Daniel Koser (IAP Goethe University Frankfurt)

3 Search for Electric Dipole Moments at COSY in Jülich - Closed-Orbit influencing Effects

The observed matter-antimatter asymmetry in the universe cannot be explained by the Standard Model (SM) of Particle Physics. In order to resolve the matter dominance an additional CP violating phenomenon is needed. A candiate for physics beyond the SM is a non-vanishing Electric Dipole Moment (EDM) of subatomic particles at the level of 10^-28 - 10^-24 e*cm. Since permanent EDMs violate parity and time reversal symmetries, they are also CP violating if the CPT-theorem is assumed. The JEDI (Jülich Electric Dipole moment Investigations) collaboration in Jülich is preparing a direct EDM measurement of protons and deuterons first at the storage ring COSY (COoler Synchrotron) and later at a dedicated storage ring. Ensuring a precise measurement, various beam and spin manipulating effects have to be considered and investigated. A distortion of the closed orbit is one of the major sources for systematic uncertainties. Therefore misalignments of magnets and residual power supply oscillations are simulated to analyse their effect on the orbit. The simulation results will be presented during the talk.

Speaker: Mrs Vera Schmidt (Forschungszentrum Jülich, IKP-4)

4 Hit reconstruction in the CBM Silicon Tracking System

The Silicon Tracking System (STS) is the main tracking appliance of the future Compressed Baryonic Matter (CBM) experiment @FAIR. The STS employs double-sided silicon micro-strip sensors with double metal layers. Here, we describe the hit reconstruction in the STS. The unbiased cluster position finding algorithm simplifies the hit error estimation and yields a spatial resolution close to that obtained with the Centre-Of-Gravity algorithm. We have developed a method to estimate the hit position error, which includes the non-uniformity of an incident particle energy loss, the detector noise, the signal discretisation, and the error introduced by the cluster position finding algorithm. A reliable estimate of the hit position error is required to obtain a valid $\chi^2$ of the track, which is further used to discard ghost track candidates. This improves the signal-to-background ratio of the reconstructed physical signals. Both the hit pull (residual/error) and the track $\chi^2$ distributions verify the viability of the method: the pull width is about 1, its shape reproduce the shape of the residual distribution, mean of the $\chi^2$ distribution is unity.

Speaker: Mrs Hanna Malygina (GSI; Goethe University Frankfurt)

Slides malygina_CBM_2017.pdf

5 Cryogenic micro-calorimeters as pixelated, high resolution x-ray detectors

Cryogenic micro-calorimeters are detectors for measuring single particle energies in the XUV to hard x-ray regime. They are operated at very low temperatures (below 100 mK) and work by detecting thermodynamic responses to the energy deposition from incident particles. Because of that, their intrinsic noise level is kept at a minimum and is mostly independent of the detected energy. In particular, metallic magnetic micro-calorimeters combine the advantages of using crystal spectrometers with a very high energy resolution (below 3 eV FWHM) and semiconductor detectors with a wide dynamic range over several magnitudes of particle energies. Recent developments in multipixel calorimeters therefore made these detectors a promising tool for the usage in spectroscopy and imaging applications. However, the utilization of micro-calorimeters is still challenging since they require complex setups and read-out systems. In the frame of this work, a scheme is presented to make the application of micro-calorimeters more feasible by introducing a digital analysis algorithm based on finite response filters. First tests on both simulated and measured data show that these filtering functions have a high performance and produce results comparable with those of more resource intensive procedures which are currently in use.

Speaker: Mr Marc Oliver Herdrich (Helmholtz-Institut Jena)

Coffee Break

Scientific Talks 2: The different topics PhD students are working on within Matter and Technology

6 Laser-based particle accelerators at HZDR

We present recent achievements towards laser-based particle accelerators gained on our in-house ultra-high intensity laser Draco. Electron acceleration experiments were performed, investigating relativistic non-linear Thomson scattering and laser-wakefield acceleration (LWFA), in case of the latter aiming especially for ionization injection while deploying advanced electron bunch structure diagnostics. Subsequent to our recent laser upgrade to the PW class, ion acceleration experiments towards tumor treatment are just within reach. Preliminary studies characterizing the generated proton beams are shown and put into perspective regarding upcoming in-vivo irradiation experiments.

Speakers: Alexander Köhler (Helmholtz-Zentrum Dresden-Rossendorf), Mrs Lieselotte Obst (Helmholtz-Zentrum Dresden-Rossendorf)

7 PIConGPU – the 3D3V particle-in-cell code developed at HZDR – a status update

PIConGPU is currently the fastest particle-in-cell code in the world. New physics models are continuously developed and, after thorough testing, included in our open-source software. In this talk we will give an overview on the recent upgrades in PIConGPU, covering new ionization schemes including ADK, Keldysh and collisional ionization, a QED and bremsstrahlung module that brings photons to the code, and various new laser implementations to better model lasers used in experiments and to enable the simulation of novel light source concepts like TWTS. We will present various synthetic diagnostic methods such as the spectrally resolved radiation detectors, the in-situ phase space diagnostic and our ParaTAXIS framework, which is able to simulate small angle photon scattering of an external x-ray pulse probing laser-driven solid-density targets. Furthermore, we will briefly discuss numerous code improvements which boost performance, unify data exchange and analysis via the openPMD standard for open, reproducible science, and our steerable live visualization. Finally we will showcase several simulations ranging from laser wakefield acceleration via ionization injection, to ion acceleration via laser interaction with spherical, perfectly isolated, mass-limited targets (both experimentally realized) to radiation signatures of a shear surface instability.

Speakers: Mr Axel Garten (HZDR), Mr Axel Huebl (HZDR), Mr Richard Pausch (HZDR)

8 Neutralized drift compression for short intense ion pulses

The Neutralized Drift Compression eXperiment II (NDCX-II) is an ion accelerator at Lawrence Berkeley National Laboratory with the intention to study ion-driven high energy density physics relevant to inertial fusion energy research in the warm dense matter regime. Simulations have shown that a target heating up to 1 eV is possible for an area in the order of mm² at thin metal foils by using uniform Bragg peak heating from 1 MeV Helium. The accelerator manages to compress the initial beam pulse by a factor of 100 in longitudinal direction and by a factor of more than 10 in radial direction. This is made possible by applying a ramped acceleration voltage that creates an inverted head to tail velocity profile. To overcome the limitations of space charge, NDCX-II uses beam propagation areas where a surrounding plasma provides free electrons to neutralize the beam and to enable further compression. With this unique capabilities NDCX-II offers new insights into beam dynamics and provides a platform for target experiments at the same time.

Speaker: Marc Zimmer (TU Darmstadt)

9 Commissioning of a 2D Si(Li) Compton polarimeter

The study of particle and photon polarization phenomena occurring in the interaction of fast ion and electron beams with matter is of particular relevance for the understanding of cosmic and laboratory plasmas where high temperatures, high atomic charge-states and high field strengths prevail. In addition, polarization-sensitive studies of radiative processes in highly-charged, heavy ions may provide detailed insights in both relativistic particle dynamics as well as QED effects and other atomic structure properties at extreme electromagnetic field strengths. Moreover, x-ray polarimetry was proposed as a tool for diagnosis of spin-polarized ion beams. Owing to the recent progress in x-ray detector technology, accurate measurements of the linear polarization for hard x-ray photons as well as the determination of the polarization orientation have become possible. To strengthen the instrumentation portfolio in line with the scientific program of the SPARC pillar of FAIR a novel Si(Li)-Compton polarimeter was build and recently commissioned in a test experiment at the ESR storagering of the GSI accelerator facility. I will present a preliminary analysis of the data obtained with the new instrument.

Speaker: Mr Marco Vockert (Institut für Optik und Quantenelektronik, FSU Jena)

Coffee Break

Scientific Talks 3: The different topics PhD students are working on within Matter and Technology

10 Enhanced lateral drift sensors: simulation and production.

One of the main goals in the R&D of tracker sensors technology is to improve the position resolution of the particle detector. There are two ways to achieve this. The most common way is to decrease the size of the read-out cell, i.e. to decrease the pixel or strip pitch. But in this case, the number of channels increases, which requires an increased bandwidth for the read-out. The other possibility to improve the position resolution of sensors is to increase the lateral size of the charge distribution already during the drift in the sensor material. In this case, it is necessary to carefully engineer the electric field in the bulk of this so-called enhanced lateral drift (ELAD) sensor. This new design is using implants deep inside the bulk. Implants constitute volumes with different values of doping concentration in comparison to the concentration in the bulk. This allows for modification of the drift path of the charge carriers in the sensor. The development of such a detector requires a good understanding of the entire production process. In order to find an optimal geometry and design of the detector, it is necessary to make reliable simulations, which are conducted using SYNOPSYS TCAD. The parameters that need to be defined are the geometry of the implants, their doping concentration and the position inside the sensor. For a realistic modeling of such implants, process simulations are used to provide input of their production-determined shapes. The production of these sensors will be based on the simulations results. In this talk, the concept of ELAD is described. TCAD simulations and a description of the production process are presented.

Speaker: Ms Anastasiia Velyka (CMS)

Slides MT2.pdf

11 Measurement of the Lorentz angle in CMS pixel detector modules

For the upgrade of the CMS experiment, the previous pixel detector is replaced by a new, four layer pixel detector during the extended 2016/17 shutdown. By using a new readout chip the detector will be able to operate at instantaneous luminosities of up to 2 x 10^34 cm^-2 s^-1 without significant efficiency losses. In the pixel detector barrel the 3.8 T magnetic field of the CMS solenoid will, due to deflection of the drifting charge carriers in the 285 um thick silicon sensor, cause charge sharing along the short side of the 150 um 100 um pixel cells and thus improve the intrinsic resolution of the detector modules. The Lorentz angle in the CMS barrel pixel detector modules was measured at the DESY Test Beam Facility using a 1.3 T magnetic field. Furthermore, simulations of the setup based on the AllPix framework and the pixelav package were performed. In this contribution the experimental setup is presented, measurement and simulation results are shown and compared.

Speaker: Mr Paul Schuetze (CMS)

12 DAQ Test System for CMS Tracker Upgrade Phase 2

For the upcoming high-luminosity phase of the LHC, the tracking detector of the CMS experiment has to be upgraded. Two types of detector modules are foreseen to be used for the outer tracker regions: so-called 2S and PS modules. Each module type consists of two semiconductor sensors with corresponding front-end electronics for the readout. For the future module production at DESY, testing infrastructure is being developed, based on the FC7 board. The FC7 is a 𝜇TCAcompatible Advanced Mezzanine Card for generic data acquisition and control applications. Developed by Imperial College London and built around the Xilinx Kintex 7 FPGA, the FC7 provides a large array of configurable I/O ports, primarily delivered by on-board FPGA Mezzanine Card (FMC) headers, which give the opportunity to establish an optical or electrical interface between the FC7 and the front-end electronics of the CMS tracker’s modules. This talk will present the development status of the FC7 firmware and very first test results.

Speaker: Mr Mykyta Haranko (DESY)

Slides haranko_mt2017_student_retreat.pdf

17:50 Break

Evening program

Tuesday, 31 January

Scientific Talks 4: The different topics PhD students are working on within Matter and Technology

13 The Barrel DIRC detector at PANDA

The PANDA experiment at the future FAIR facility will use antiproton annihilations to investigate open questions in hadron physics in the momentum range of 1.5-15 GeV/c. A Barrel DIRC detector will be built for the PANDA target spectrometer in order to achieve excellent charged particle identification (PID), which is needed to cleanly separate π/K/p. Based on the successful BaBar DIRC detector with added key improvements, this detector will perform a better-than 3σ π/k separation in the momentum range of 0.5 GeV/c to 3.5 GeV/c and in the polar angle range of 22° to 140°. The Barrel DIRC counter will use enhanced-lifetime MCP-PMTs for photon detection in combination with fast readout electronics. The radiators are made from highly polished synthetic fused silica to ensure that photons, propagating through the radiators by total internal reflection, conserve the Cherenkov angle and reach the photon detection plane without angular distortions. The DIRC principle, key components and the expected PID performance will be presented in this talk.

Speaker: Mr Marvin Krebs (GSI Helmholtzzentrum fuer Schwerionenforschung GmbH)

Slides helmholtz_mt_barreldirc_MK.pdf

14 ROPPERI - A TPC readout with Timepix and pads

For the International Large Detector (ILD) at the planned International Linear Collider (ILC) a Time Projection Chamber (TPC) is foreseen as central tracker. The electrons produced in the TPC gas volume are amplified by Micro Pattern Gaseous Detectors (MPGDs). One possibility is the usage of Gaseous Electron Multiplier (GEM) foils that amplify the electrons and project the charge cloud onto a segmented anode plane. This work investigates a novel anode readout structure with small pads on a separate PCB (for flexibility) and a pixel chip as on-board digitization electronics (for high integration). The small pads allow for the identification of the initial electron clusters which leads to an improvement of particle identification capabilities via dE/dx.

Speaker: Ulrich Einhaus (FLC)

15 Silicon photomultiplier for space application

The development of Silicon Photomultipliers (SiPMs) made great progress in the last years. Compared to conventional Multi Anode Photomultiplier Tubes (MAPMTs), SiPMs have several advantages like a low bias voltage and a robust structure, but also disadvantages like a high temperature dependence and a high dark count rate. To investigate the possibility of replacing conventional MAPMTs with SiPMs, the 'Silicon Elementary Cell Add-on' (SiECA) is under development. The aim of SiECA is the detection of Ultra-High Energy Cosmic Rays (UHECRs) with SiPMs within the frame of the 'Extreme Universe Space Observatory' (EUSO) pathfinder experiment 'EUSO- Super Pressure Balloon'. In this context, 64 channel SiPM arrays of the newest series manufactured by Hamamatsu have been studied and characterized. During the presentation, the working principle of SiPM will be described and an comparison to MAPMTs will be made. SiECA will be described and some characterization results of the newest SiPM series will be presented.

Speaker: Mr Max Renschler (Karlruher Institut für Technologie)

16 HILITE - High-Intensity Laser Ion-Trap Experiment

We are currently setting up a Penning-trap experiment to investigate laser-ion interaction in high-intensity photon fields and study non-linear processes like multi-photon and tunnel ionization of trapped ions. The setup is designed to be transported to different high-intensity laser facilities, like FLASH at DESY, or JETI/POLARIS in Jena. The trap is designed as an open-endcap Penning trap, which allows free access from both sides for particle loading and the laser beam. Beside the two endcap electrodes, it consists of a split-ring electrode for excitation and detection in the center and two conical-shaped capture electrodes for dynamic capture of ions from external sources. A non-destructive detection technique of the ion motion, as well as a selection of specific ion species of interest will be implemented. The complete setup is located at the center of a superconducting magnet with a field strength of up to 6 T. A pulse-tube cooler is used for cooling the trap and the electronics to 4 K. Initially, a Ti:sapphire laser system with 10 mJ pulse energy and a pulse duration of 30 fs will be used.

Speaker: Mr Nils Stallkamp (GSI; Helmholtz Institut Jena)

17 Photonic Chip & System Design for Terabit/s Optical Data Transmission

Future detectors will consist of many millions up to billions individual channels resulting in massive raw data, to develop corresponding readout system is a key problem. IPE, KIT proposed a novel high-speed optical data transmission system based on wavelength division multiplexer. This report will introduce the novelty of the concept, the comprised components of the system and some techniques used in the design.

Speaker: Zhang Yunlong (IPE, KIT)

Coffee Break

Discussion: PhD Students within the Helmholtz Association

Lunch