Automated assembly of large double-sided microstrip detector modules of the CBM Silicon Tracking System at FAIR

The detector modules of the Silicon Tracking System of the Compressed Baryonic Matter experiment at FAIR comprise double-sided silicon microstrip sensors with a size of up to 124 mm x 62 mm. Due to tight material budget constraints, the sensors are connected to the read-out electronics by long flexible microcables. As manual assembly of the modules is time-consuming and difficult, a fully customized in-house bonder machine has been developed which allows for a highly automated detector module assembly. We present the requirements and the setup of the bonder machine together with the achieved alignment accuracy and first assemblies

Novel production method for large double-sided microstrip detectors of the CBM Silicon Tracking System at FAIR

The silicon sensors of the Silicon Tracking System of the Compressed Baryonic Matter experiment at FAIR, GSI are connected to the read-out electronics by low mass flexible microcables due to tight material budget restrictions. The cable length of up to 50 cm and its flexible nature make detector module assembly one of the most critical parts in STS. A novel low mass, low capacitance multilayer copper microcable has been designed and produced to facilitate detector assembly. Furthermore, a novel detector production method based on high-density gold stud bump bonding of silicon die on microcable has been developed. We present the Cu microcable design, capacitance simulations and measurements together with the individual steps performed in the STS detector assembly

Poorer outcome of elderly patients treated with extended-field radiotherapy compared with involved-field radiotherapy after chemotherapy for Hodgkin's lymphoma: an analysis from the German Hodgkin Study Group

Background: The optimal treatment of elderly patients with Hodgkin's lymphoma (HL) is still a matter of debate. Since many of these patients receive combined modality treatment, we evaluated the impact of different radiation field sizes, that is extended-field (EF) or involved-field (IF) technique when given after four cycles of chemotherapy. Patients and methods: In the multicenter HD8 study of the German Hodgkin Study Group, 1204 patients with early-stage unfavorable HL were randomized to receive four cycles of chemotherapy followed by either radiotherapy (RT) of 30 Gy EF + 10 Gy to bulky disease (arm A) or 30 Gy IF + 10 Gy to bulky disease (arm B). A total of 1064 patients were assessable for the analysis. Of these, 89 patients (8.4%) were 60 years or older. Results: Elderly patients had a poorer risk profile. Acute toxicity from RT was more pronounced in elderly patients receiving EF-RT compared with IF-RT [World Health Organization (WHO) grade 3/4: 26.5% versus 8.6%)]. Freedom from treatment failure (FFTF, 64% versus 87%) and overall survival (OS, 70% versus 94%) after 5 years was lower in elderly patients compared with younger patients. Importantly, elderly patients had poorer outcome when treated with EF-RT compared with IF-RT in terms of FFTF (58% versus 70%; P = 0.034) and OS (59% versus 81%; P = 0.008). Conclusion: Elderly patients with early-stage unfavorable HL generally have a poorer risk profile and outcome when compared with younger patients. Treatment with EF-RT instead of IF-RT after chemotherapy has a negative impact on survival of elderly patients and should be avoide

Non-local kinetic and macroscopic models for self-organised animal aggregations

The last two decades have seen a surge in kinetic and macroscopic models derived to investigate the multi-scale aspects of self-organised biological aggregations. Because the individual-level details incorporated into the kinetic models (e.g., individual speeds and turning rates) make them somewhat difficult to investigate, one is interested in transforming these models into simpler macroscopic models, by using various scaling techniques that are imposed by the biological assumptions of the models. However, not many studies investigate how the dynamics of the initial models are preserved via these scalings. Here, we consider two scaling approaches (parabolic and grazing collision limits) that can be used to reduce a class of non-local 1D and 2D models for biological aggregations to simpler models existent in the literature. Then, we investigate how some of the spatio-temporal patterns exhibited by the original kinetic models are preserved via these scalings. To this end, we focus on the parabolic scaling for non-local 1D models and apply asymptotic preserving numerical methods, which allow us to analyse changes in the patterns as the scaling coefficient ϵ is varied from ϵ=1 (for 1D transport models) to ϵ=0 (for 1D parabolic models). We show that some patterns (describing stationary aggregations) are preserved in the limit ϵ→0, while other patterns (describing moving aggregations) are lost. To understand the loss of these patterns, we construct bifurcation diagrams

Upconversion-induced heat generation and thermal lensing in Nd:YLF and Nd:YAG

We investigate the influence of interionic upconversion between neighboring ions in the upper laser level of Nd:YLF and Nd:YAG on population dynamics, heat generation, and thermal lensing under lasing and non-lasing conditions. It is shown that cascaded multiphonon relaxations following each upconversion process generate significant extra heat dissipation in the crystal under non-lasing compared to lasing conditions. Owing to the unfavorable temperature dependence of thermal and thermo-optical parameters, this leads, firstly, to a significant temperature increase in the rod, secondly, to strong thermal lensing with pronounced spherical aberrations and, ultimately, to rod fracture in a high-power end-pumped system. In a three-dimensional finite-element calculation, excitation densities, upconversion rates, heat generation temperature profiles, and thermal lensing are calculated. Differences in thermal lens power between non-lasing and lasing conditions up to a factor of six in Nd:YLF and up to a factor of two in Nd:YAG are experimentally observed and explained by the calculation. This results in a strong deterioration in performance when operating these systems in a Q-switched regime, as an amplifier, or on a low-gain transition. Methods to decrease the influence of interionic upconversion are discussed. It is shown that tuning of the pump wavelength can significantly alter the rod temperature

MODELLING OF MODE OVERLAP IN LONGITUDINALLY PUMPED SOLID STATE LASERS

In our paper we investigated the influence of the mode overlap on the efficiency of longitudinally pumped solid state lasers. In a theoretical part we enhanced an existing model for four level lasers from idealized cylindrical modes to arbitrary pump and laser modes in a random relative position. Theoretical predictions were confirmed experimentally with an end-pumped Nd:YAG rod operated at 1064 nm. To investigate the effect of misalignment on the efficiency we used a Ti-Sapphire pump laser which could be displaced relative to the laser beam. In a second experiment a diode laser equipped with coupling optics served as the pump source for the same resonator. This resulted in a 20 % decrease in slope efficiency compared to the Ti-Sapphire pumped system due to the limited mode overlap produced by the diode coupling optics