Energy Loss Signals in the ALICE TRD

We present the energy loss measurements with the ALICE TRD in the $\beta\gamma$ range 1--10$^{4}$, where $\beta=v/c$ and $\gamma=1/\sqrt{1-\beta^2}$. The measurements are conducted in three different scenarios: 1) with pions and electrons from testbeams; 2) with protons, pions and electrons in proton-proton collisions at center-of-mass energy 7 TeV; 3) with muons detected in ALICE cosmic runs. In the testbeam and cosmic ray measurements, ionization energy loss (dE/dx) signal as well as ionization energy loss plus transition radiation (dE/dx+TR) signal are measured. With cosmic muons the onset of TR is observed. Signals from TeV cosmic muons are consistent with those from GeV electrons in the other measurements. Numerical descriptions of the signal spectra and the $\beta\gamma$-dependence of the most probable signals are also presented.Comment: Proceedings for the 4th Workshop on Advanced Transition Radiation Detectors for Accelerator and Space Applications, 14-16 September 2011, Bari, Ital

Firmware Development and Integration for ALICE TPC and PHOS Front-end Electronics: A Trigger Based Readout and Control System operating in a Radiation Environment

The readout electronics in PHOS and TPC - two of the major detectors of the ALICE experiment at the LHC - consist of a set of Front End Cards (FECs) that digitize, process and buffer the data from the detector sensors. The FECs are connected to a Readout Control Unit (RCU) via two sets of custom made PCB backplanes. For PHOS, 28 FECs are connected to one RCU, while for TPC the number is varying from 18 to 25 FECs depending on location. The RCU is in charge of the data readout, including reception and distribution of triggers and in moving the data from the FECs to the Data Acquisition System. In addition it does low level control tasks. The RCU consists of an RCU Motherboard that hosts a Detector Control System (DCS) board and a Source Interface Unit. The DCS board is an embedded computer running Linux that controls the readout electronics. All the mentioned devices are implemented in commercial grade SRAM based Field Programmable Gate Arrays (FPGAs). Even if these devices are not very radiation tolerant, they are chosen because of their cost and flexibility, and most importantly the possibility to easily do future upgrades of the electronics. Since physical shielding of the electronics is not possible in ALICE due to the architecture of the detector, the radiation related errors need to be handled with other techniques such as firmware mitigation techniques. The main objective of this thesis has been to make firmware modules for the FPGAs reciding in different parts of the readout electronics. Because of the flexibility of the designs, some of them have, with minor adaptations, been applied in different devices surrounding the readout electronics. Additionally, effort has been put into testing and integration of the system. In detail, the work presented in this thesis can be summarized as follows: - Firmware design for radiation environments. All firmware modules that are designed are to be used in a radiation environment, and then special precautions need to be taken. Additionally, a state-of-the-art solution has been designed for protecting the main FPGA on the RCU Motherboard against radiation induced functional failures. - Implementation of Trigger Handling for the TPC/PHOS Readout Electronics. The triggers are received from the global trigger system via an optical link and are handled by an Application Spesific Integrated Circuit (ASIC) on the DCS board. The problem is that the DCS board might have occasional down time 6 due to radiation related errors, so a special interface module is designed for the main FPGA on the RCU Motherboard. This module decodes and verifies the information received from the trigger system. As it is a generic design it has also been implemented as part of the BusyBox. The BusyBox is an important device in the trigger path of the TPC and PHOS sub-detectors. - Testing and Verification of all firmware modules. All firmware modules have been extensively verified with computer simulation before being tested in real hardware. - Maintenance of the DCS board for TPC/PHOS and of the different Fee firmware modules in general. - System Integration and System Level Tests. A big contribution has been done integrating and testing all the modules and sub-systems. This concern both locally on the RCU and the BusyBox, as well as making all the devices play together on a larger scale. - Testing and Verification of all firmware modules. All firmware modules have been extensively verified with computer simulation before being tested in real hardware. - Maintenance of the DCS board for TPC/PHOS and of the different Fee firmware modules in general. - System Integration and System Level Tests. A big contribution has been done integrating and testing all the modules and sub-systems. This concern both locally on the RCU and the BusyBox, as well as making all the devices play together on a larger scale. As the presented electronics are located in a radiation environment and are physically unavailable after commissioning, effort has been put into making designs that are reliable, scalable and possible to upgrade. This has been ensured by following a systematic design approach where testability, version management and documentation are key elements. Some parts of the work described in this thesis have been published and presented in international peer reviewed publications and conferences

Korleis blir friluftsliv framstilt og forstått i den vidaregåande skulen: Ein kvalitativ undersøking av korleis kroppsøvingslærarar og rektorar opplever og erfarar friluftsliv i kroppsøvingsundervisninga

Føremålet med prosjektet er å belyse friluftslivemnet i kroppsøvingsfaget. Prosjektets problemområde tar for seg korleis friluftslivomgrepet blir oppfatta og framstilt, kva plass har det i skulen, vekting i læreplanen og korleis det blir praktisert i undervisning, ved hjelp av å ta tak i kroppsøvingslærarar og rektorar sine forståingar og meiningar kring tema. For innsamling av datamateriale blei det nytta kvalitativt intervju som metode. Utvalet i undersøkinga bestod av 6 informantar frå to ulike vidaregåande skular, ein byskule og ein distriktskule. Informantane var fordelt slik, 1 rektor og 2 kroppsøvingslærarar per skule

Proton tracking in a high-granularity Digital Tracking Calorimeter for proton CT purposes

Radiation therapy with protons as of today utilizes information from x-ray CT in order to estimate the proton stopping power of the traversed tissue in a patient. The conversion from x-ray attenuation to proton stopping power in tissue introduces range uncertainties of the order of 2-3% of the range, uncertainties that are contributing to an increase of the necessary planning margins added to the target volume in a patient. Imaging methods and modalities, such as Dual Energy CT and proton CT, have come into consideration in the pursuit of obtaining an as good as possible estimate of the proton stopping power. In this study, a Digital Tracking Calorimeter is benchmarked for proof-of-concept for proton CT purposes. The Digital Tracking Calorimeteris applied for reconstruction of the tracks and energies of individual high energy protons. The presented prototype forms the basis for a proton CT system using a single technology for tracking and calorimetry. This advantage simplifies the setup and reduces the cost of a proton CT system assembly, and it is a unique feature of the Digital Tracking Calorimeter. Data from the AGORFIRM beamline at KVI-CART in Groningen in the Netherlands and Monte Carlo simulation results are used to in order to develop a tracking algorithm for the estimation of the residual ranges of a high number of concurrent proton tracks. The range of the individual protons can at present be estimated with a resolution of 4%. The readout system for this prototype is able to handle an effective proton frequency of 1 MHz by using 500 concurrent proton tracks in each readout frame, which is at the high end range of present similar prototypes. A future further optimized prototype will enable a high-speed and more accurate determination of the ranges of individual protons in a therapeutic beam.Comment: 21 pages, 8 figure

Multi-strange baryon measurements at LHC energies, with the ALICE experiment

The status of the charged multi-strange baryon analysis (Xi-, anti-Xi+, Omega-, anti-Omega+) at LHC energies is presented. This report is based on the results obtained with ALICE (A Large Ion Collider Experiment), profiting from the characteristic cascade-decay topology. A special attention is drawn to the early pp data-taking period (2009-2010) and subsequently, on the uncorrected pT-spectra extracted at mid-rapidity for centre of mass energies of 0.9 TeV and 7 TeV.Comment: 4 pages, 5 figures, Hot Quarks 2010 proceedings, La Londe Les Maures, France, June 2010 (to be published in Journal of Physics: Conference Series

Sgr A* as probe of the theory of supermassive compact objects without event horizon

In the present paper some consequences of the hypothesis that the supermassive compact object in the Galaxy centre relates to a class of objects without event horizon are examined. The possibility of the existence of such objects was substantiated by the author earlier. It is shown that accretion of a surrounding gas can cause nuclear combustion in the surface layer which, as a result of comptonization of the superincumbent hotter layer, may give a contribution to the observed Sgr A* radiation in the range $10^{15} \div 10^{20} Hz$. It is found a contribution of the possible proper magnetic moment of the object to the observed synchrotron radiation on the basis of Boltzmann's equation for photons which takes into account the influence of gravity to their motion and frequency. We arrive at the conclusion that the hypothesis of the existence in the Galaxy centre of the object with such extraordinary gravitational properties at least does not contradict observations.Comment: Final version, Latex, 10 pages, 7 figure. Accepted to Astron. Nach