New measurements of the antiproton flux and the antiproton-to-proton flux ratio at the top of the atmosphere between 80 MeV and 2.0 GeV are presented. The measurement was conducted from July 2006 to March 2008 with the PAMELA satellite experiment. This is a period of minimum solar activity and negative solar polarity and the PAMELA measurement is the first observation of antiprotons during this particular solar state. The PAMELA instrument comprises a permanent magnet spectrometer, a scintillator based time-of-flight system, an electromagnetic calorimeter and an anticoincidence shield. These detectors can identify antiprotons from a background of cosmic-ray electrons and locally produced pions. The PAMELA instrument is mounted on the Resurs DK1 satellite that was launched from the Baikonur Cosmodrome on June the 15th into a semi-polar orbit with an inclination of 70o. During approximately 500 days of data collection 170 antiprotons were identified. The derived antiproton spectrum shows a steep increase up to 2 GeV as expected for pure secondary production of galactic antiprotons. The antiproton flux is over-estimated by most current models of secondary production compared to PAMELA results. There are no indications of the excess of antiprotons at low energy predicted by theories of primordial black hole evaporation. The antiproton-to-proton flux ratio is in agreement with drift models of solar modulation, which are also favoured by recent PAMELA measurements of the positron fraction. / QC 20100811

The Kompaneets equation describes the spectrum formation when hot fermions are injected into an opaque fermion-photon plasma in thermal equilibrium and inverse Compton-scatterings occur. The equation has three free parameters, the initial plasma thermal energy θ_u, the final plasmathermal energy θ_r and the average photon energy gain y_r. In this study I use the parameters R = θ_r/θ_u, θ_r and y_r. The created spectrum has different properties, of which an important one is the mean photon energy ε_d. In this thesis, I aim to find the dependencies of the mean photon energy on the three Kompaneets parameters. I chart the parameter spaces and find correlation between the mean photon energy and the individual parameters. I describe the relations between the mean photon energy and the Kompaneets quantities empirically, constructing a function where I try to separate the variables as far as possible. For general results, I study a wide range of each parameter, which forces me to make a broken power-law description of the mean energy. I arrive at a function of the form ε_d(R, y_r, θ_r) = g(R, y_r) R^k(y_r) 3θ_r. I perform an error analysis and see that the majority of the errors of the new method is ≲ 2%, while the previous (tabulated value based approximation) method had the majority of the errors ≲ 70%. This means an effective improvement of the method by a factor 35. Then, I discuss the behaviour of the mean energy in the Kompaneets parameterspace. Finally, I outline a similar analysis of another property of the Kompaneets spectrum, the Compton temperature. / Kompaneetsekvationen beskriver hur spektrumet bildas när högenergetiska elektroner injiceras i en ogenomskinlig fermion-fotonplasma i termisk jämvikt och när dessa växelverkar genom invers Comptonspridning. Ekvationen har tre fria parametrar, termiska energin före och efter injektionen i plasman, θ_u respektive θ_r samt den genomsnittliga energivinsten yr hos fotonerna. I denna studie används parametrarna R = θ_u/θ_r, θ_r och y_r. Det bildade spektrumet har olika egenskaper, varav en viktig är medelenergin ε_d hos fotonerna. I denna uppsats undersöks medelenergins parameterberoenden på de tre Kompaneetsparametrarna. Genom att parameterrummen kartläggs, hittas det korrelation empiriskt mellan medelenergin och Kompaneetsstorheterna. På detta vis bygger jag upp en funktion där jag tillämpar variabelseparation så gott det går. För att erhålla allmänna resultat undersöks breda intervall i varje parameter. Detta tvingar mig att konstruera en s. k. bruten potenslagsbeskrivning av medelenergin. Resultatet blir en funktion på formen ε_d(R, y_r, θ_r) = g(R, y_r) R^k(y_r) 3θ_r. En felanalys utförs, vilken visar att merparten av felen i den nya metoden är ≲ 2%. Detta kan jämföras med den föregående approximationsmetoden (baserad på tabellerade värden), som hade merparten av felen ≲ 70%. Detta innebär en metodförbättring med en faktor 35. Sedan diskuteras beteendet av medelenergin i parameterrummet. Till slut skisseras en liknande analys av en annan viktig spektrumegenskap, Comptontemperaturen.

CUBES is an X-ray detector that will be placed aboard the KTH 3U CubeSat mission, MIST. Its purpose is to detect high energy X-rays as well as to test various components in a space environment. Two CUBES will be placed on the satellite. Each CUBES consists of a printed circuit board (PCB) with three multi pixel photon counters (MPPCs). On top of these, three Germanium Aluminium Gadolinium Garnet (GAGG) scintillators are glued. These GAGG scintillators are of the dimension 1X1X1 cm^3 and are covered with PTFE tape and an opaque potting compound to prevent photons from leaving the scintillator. The MPPCs consists of a large amount of semi conductors operated in Geiger mode. The data is processed by an application specific integrated circuit (ASIC). In order to prepare the CUBES instrument for satellite flight, energy and thermal characterisation have been performed. The energy range was determined to be 40-1200 keV. The detector system shows linear behaviour and operates stably in a temperature range of -20 °C to +30 °C. The preparation of the boards and test results are presented in this thesis. / CUBES är en röntgendetektor som kommer att placeras ombord på KTH 3U CubeSat satelliten MIST. Uppdraget är att undersöka högenergetisk röntgenstrålning samt att testa komponenternas robusthet i rymden. Två CUBES kommer att placeras ombord på satelliten. CUBES detektorn består av ett kretskort med 3 MPPC (multi pixel photon counters). Ovanpå dessa är tre Germanium Aluminium Gadolinium Garnet (GAGG) scintillatorer limmade. Dessa GAGG scintillatorer har dimensionerna 1X1X1 cm^3, är täckta med PTFE band och är inneslutna i ett opakt gummi ämne för att förhindra att fotoner lämnar detektorn. MPPC består av en stor mängd halvledare som drivs i Geiger läge. Den producerade datan kommer att behandlas av en applikations specifik integrerad krets (ASIC). Inför CUBES detektorns uppdrag i rymden utfördes energi och värmetest. Det tillgängliga energiintervallet uppmättes till 40-1200 keV. Detektorn uppvisar ett linjärt energiförhållande och ger ett stabilt resultat i temperaturintervallet -20 °C till +30 °C. Resultaten av mätningarna samt förberedandet av CUBES detektorerna presenteras i denna avhandling.

Polarisation of X-ray light is being investigated with polarimeters to extend the borders of what can be observed. Distant compact objects, such as pulsars, that are to small on the sky to be analysed with imaging can be investigated by analysing the polarisation of the emitted light. This can reveal physics previously hidden by their small nature. There are many models that aim to describe the polarisation of these compact objects to make sense of what is measured. Two examples are the outer gap and two-pole caustic models. The X-ray polarimeter XL-Calibur is a balloon-borne telescope capable of detecting X-rays in the $15-80$ keV energy range. In this thesis details on the polarisation of light, how it can be measured and some principles of X-ray polarimetery is discussed. A new feature in the simulation of XL-Calibur in Geant4 is also described and used to investigate the possibility for XL-Calibur to distinguish between different Crab pulsar polarisation models at different signal rates. The results show that signal rates under 2 Hz yield insufficient data to distinguish between the two models using the measured polarisation fraction and angle. For greater signal rates XL-Calibur does in fact differentiate between the models correctly. New methods for the statistical analysis of data can be explored to allow more data to be salvaged, even for low signal rates. The derivation of polarisation parameters is fixed through Stokes parameters in this thesis. / Polarisationen av röntgenljus undersöks med polarimetrar för att utvidga gränserna för vad som kan observeras. Avlägsna kompakta objekt, såsom pulsarer, som är för små och för långt borta på himlen för att analyseras med optiska metoder, kan undersökas genom att analysera polarisationen av det utstrålade ljuset. Detta kan avslöja fysik som tidigare var dold på grund av deras storlek. Det finns många modeller som syftar till att beskriva polarisationen av dessa kompakta objekt för att förstå vad som mäts. Två exempel är modellerna: outer gap och two-pole caustic. Röntgenpolarimetern XL-Calibur är ett ballongburet teleskop som kan detektera röntgenstrålning i energiområdet $15-80$ keV. I denna avhandling diskuteras detaljer om ljusets polarisation, hur det kan mätas och några principer för röntgenpolarimetri. En ny funktion i simuleringen av XL-Calibur i Geant4 beskrivs också. Den används för att undersöka möjligheten för XL-Calibur att särskilja mellan olika polariseringsmodeller för Krabbpulsaren vid olika signaltakter. Resultaten visar att för signaltakter under 2 Hz, blir datan otillräcklig för att särskilja mellan de två modellerna både för polarisationsgraden och vinkeln. För högre signaltakter kan XL-Calibur skilja mellan modellerna. Nya metoder för statistisk analys av data kan utforskas för att möjliggöra att mer data kan användas, även för låga signaltakter. I denna avhandling beräknas polarisationsparametrarna genom Stokesparametrarna.

X-ray polarimetry, the study of the polarisation of X-ray light, is a powerful and rapidly developing tool for astrophysics, which promises to help answer outstanding questions about the physics of extreme objects such as pulsars, X-ray binaries and active galactic nuclei. The balloon-borne telescope XL-Calibur will be the first instrument to study the polarisation of hard X-rays (with energies between 10 and 100 keV) in detail, correlating with the soft X-ray observations of IXPE to provide further tests of polarisation-dependent x-ray emission models in extreme objects. The working principles of XL-Calibur are described, together with the necessary steps to measure the polarisation of X-rays. In these steps, Geant4 simulations of the telescope play a vital role, and the simulations are thus described in detail, together with the experiments done to validate the simulations. These experiments were performed at Esrange, Sweden during the XL-Calibur flight campaign in May of 2022, and the experimental setup and design of the validation experiments are described, as well as the specific simulations performed to replicate the experiment. The simulations show very good agreement with validation experiments, achieving a simulated modulation factor (a measure of the polarimetric response intrinsic to the detector) of 41.88% ± 0.17%, within one standard deviation of the measured 41.95% ± 0.18%. The optical effects of the XL-Calibur X-ray mirror is also simulated to good agreement with experimental results, necessary for simulating flight observations. Thus, the simulations can be used to simulate XL-Calibur for polarisation measurements and analysis. Furthermore, the effect on polarisation parameters of the mirror focal spot being offset is investigated. It is shown that it affects the modulation factor and thus the measured polarisation parameters, increasing the importance of using simulations to replicate and compensate for these effects during a data-taking flight with XL-Calibur. / Röntgenpolarimetri, att undersöka polariseringen hos röntgenljus, är ett kraftfullt redskap inom astrofysiken som är under snabb utveckling. Förhoppningen är att tekniken ska hjälpa till att lösa obesvarade frågor inom fysiken som beskriver extrema objekt såsom pulsarer, röntgenbinärer och aktiva galaxkärnor. Det ballongburna teleskopet XL-Calibur kommer att vara det första instrumentet som studerar polariseringen av hårda röntgenstrålar (med energi mellan 10 och 100 keV) i detalj, och genom att korrelera med IXPEs observationer i mjuka röntgenstrålar kommer polarisationsberoende modeller för bildandet av röntgenstrålar runt extrema objekt att testas. En beskrivning av hur XL-Calibur fungerar ges, tillsammans med de nödvändiga stegen för att mäta polariseringen hos röntgenljus. I dessa steg är simulering av teleskopet i Geant4 en vital del, och simuleringen beskrivs därav ingående tillsammans med experimenten som gjordes för att validera simuleringen. Dessa experiment utfördes på Esrange, Sverige i maj 2022, före XL-Caliburs första flygning. Experimentuppställningen och utformningen av dessa valideringsexperiment beskrivs tillsammans med de specifika simuleringar som gjordes med mål att replikera experimenten. Simuleringarna visar mycket god överensstämmelse med experimenten, med en modulationsfaktor (ett instrumentspecifikt mått av polarisationsgraden) på 41.88% ± 0.17%, inom en standardavvikelse från experimentens 41.95% ± 0.18%. Även de optiska effekterna från XL-Caliburs röntgenspegel simuleras och visar god överensstämmelse med mätningar, vilket är nödvändigt för att kunna simulera data tagen under en flygning. Därmed kan simuleringarna användas för att göra polarisationsmätningar och -analys. Slutligen görs en undersökning av effekten på polarisationsparametrarna av förskjutning av röntgenspegelns fokus. Denna visar att modulationsfaktorn och därmed polarisationsparametrarna ändras på ett betydande vis, vilket ökar vikten av att använda simuleringar för att reproducera och kompensera för dessa effekter under en datainsamlingsflygning med XL-Calibur.

<p>A relic density of <i>Weakly Interacting Massive Particles</i> (WIMPs) remaining from the Big Bang constitutes a promising solution to the <i>Dark Matter</i> problem. It is possible for such WIMPs to be trapped by and accumulate in gravitational potentials of massive dense objects such as the Sun. A perfect WIMP candidate appears in certain <i>supersymmetric</i> extensions to the <i>Standard Model</i> of particle physics, where the lightest supersymmetric particle is a <i>neutralino</i> which can be stable, massive and weakly interacting. The neutralinos may annihilate pair-wise and in these interactions neutrinos with energies ranging up to the neutralino mass can be indirectly produced. Hence, a possible population of dark matter neutralinos trapped in the Sun can give rise to an observable neutrino flux.</p><p>The Antarctic Muon And Neutrino Detector Array, AMANDA, is a neutrino telescope that detects Cherenkov light emitted by charged particles created in neutrino interactions in the South Pole glacial ice sheet using an array of light detectors frozen into the deep ice. In this work data taken with the AMANDA-II detector during 2003 are analyzed to measure or put upper bounds on the flux of such neutrinos from the Sun. In the analysis detailed signal and background simulations are compared to measurements. Background rejection filters optimized for various neutralino models have been constructed. No excess above the background expected from neutrinos and muons created in cosmic ray interactions in the atmosphere was found. Instead 90% confidence upper limits have been set on the neutralino annihilation rate in the Sun and the muon flux induced by neutralino signal neutrinos. </p>

PAMELA is a satellite-borne cosmic ray experiment. Its primary scientific objective is to study the antiproton and positron components of the cosmic radiation. This will be done with unprecedented statistics over a wide energy range (~10MeV to ~100GeV). The PAMELA experiment consists of a permanent magnetic spectrometer, an electromagnetic calorimeter, a Time-of-Fight system, a neutron detector and a shower tail catcher. An anticoincidence (AC) system surrounds the spectrometer to detect particles which do not pass cleanly through the acceptance of the spectrometer. PAMELA will be mounted on a Russian Earth-observation satellite, and the launch is scheduled for 2006. The anticoincidence system for PAMELA has been developed by KTH, and consists of plastic scintillator detectors with photomultiplier tube read-out. Extensive testing has been performed during the development phase. Results are presented for environmental tests, tests with cosmic-rays and particle beams. The design of the digital part of the AC electronics has been realised on an FPGA (Field Programmable Gate Array) and a DSP (Digital Signal Processor). It records signals from the 16 AC photomultipliers and from various sensors for over-current and temperature. It also provides functionality for setting the photomultiplier discrimination thresholds, system testing, issuing alarms and communication with the PAMELA main data acquisition system. The design philosophy and functionality needs to be reliable and suitable for use in a space environment. To evaluate the performance of the AC detectors, a test utilizing cosmic-rays has been performed. The primary aim of the test was to calibrate the individual channels to gain knowledge of suitable discriminator levels for flight. A secondary aim was to estimate the AC detector efficiency. A lower limit of (99.89±0.04)% was obtained. An in-orbit simulation study was performed using protons to estimate trigger rates and investigate the AC system performance in a second level trigger. The average orbital trigger rate was estimated to be (8.4±0.6)Hz, consisting of (2.0±0.2)Hz good triggers and (6.4±0.5)Hz background. Inclusion of the AC system in the trigger condition to reduce background (for the purpose of data handling capacity) leads to losses of good triggers due to backscattering from the calorimeter (90% loss for 300GeV electrons and 25% for 100GeV protons). A method, using the calorimeter, for identifying backscattering events was investigated and found to reduce the loss of good events to below 1% (300GeV electrons) and 5% (100GeV protons), while maintaining a background reduction of 70%. of 70%. / QC 20101019

A relic density of Weakly Interacting Massive Particles (WIMPs) remaining from the Big Bang constitutes a promising solution to the Dark Matter problem. It is possible for such WIMPs to be trapped by and accumulate in gravitational potentials of massive dense objects such as the Sun. A perfect WIMP candidate appears in certain supersymmetric extensions to the Standard Model of particle physics, where the lightest supersymmetric particle is a neutralino which can be stable, massive and weakly interacting. The neutralinos may annihilate pair-wise and in these interactions neutrinos with energies ranging up to the neutralino mass can be indirectly produced. Hence, a possible population of dark matter neutralinos trapped in the Sun can give rise to an observable neutrino flux. The Antarctic Muon And Neutrino Detector Array, AMANDA, is a neutrino telescope that detects Cherenkov light emitted by charged particles created in neutrino interactions in the South Pole glacial ice sheet using an array of light detectors frozen into the deep ice. In this work data taken with the AMANDA-II detector during 2003 are analyzed to measure or put upper bounds on the flux of such neutrinos from the Sun. In the analysis detailed signal and background simulations are compared to measurements. Background rejection filters optimized for various neutralino models have been constructed. No excess above the background expected from neutrinos and muons created in cosmic ray interactions in the atmosphere was found. Instead 90% confidence upper limits have been set on the neutralino annihilation rate in the Sun and the muon flux induced by neutralino signal neutrinos.

PAMELA is a satellite-borne experiment designed to study the charged component of the cosmic radiation of galactic, solar and trapped nature. The main scientific objective is the study of the antimatter component of cosmic rays over a wide range of energies (antiprotons: 80 MeV–190 GeV, positrons: 50 MeV–270 GeV). PAMELA is also searching for antinuclei with a precision ~10^−7 in anti-He/He measurements. PAMELA is mounted on the Resurs DK1 satellite that was launched on June 15th 2006 from the Baikonur cosmodrome and is now on a semipolar (69.9°) elliptical (350 × 600 km) orbit. The experiment has been acquiring data since July 11th 2006 and has a foreseen lifetime of at least 3 years. The PAMELA apparatus consists of a permanent magnet silicon spectrometer, an electromagnetic imaging calorimeter, a time of flight system, a scintillator-based anticoincidence (AC) system, a tail catcher scintillator and a neutron detector. The AC system can be used to reject particles not cleanly entering the PAMELA acceptance. Tests of the PAMELA instrument in its final flight configuration involved long duration acquisition runs with cosmic particles (mainly muons) on ground. A study of the functionality of the AC system during these runs is presented here with a set of selected muons. Studies of activity in the AC detectors as function of the rigidity of the muons and in correlation with the activity in the spectrometer and in the calorimeter are presented. A study of the AC system functionality during in-flight operations provides a map of the particle flux in orbit, and shows the anisotropy in the arrival direction of trapped particles in the Van Allen radiation belts. The singles rates indicate that the AC system saturates in the South Atlantic anomaly (SAA). Information from the AC system in the SAA is therefore not reliable for physics analysis. The timing and multiplicity of AC activity correlated to particle triggers has been studied. A dependence on orbital position was observed. An LED (Light Emitting Diode) based monitoring system was designed to determine the in-orbit behaviour of the AC system independently of the radiation environment and to compare it to the pre-launch behaviour. The LED system shows that the properties of the AC system are stable during flight and that no significant changes in performance occurred as a result of the launch. / QC 20100811

<p>PAMELA is a satellite-borne cosmic ray experiment. Its primary scientific objective is to study the antiproton and positron components of the cosmic radiation. This will be done with unprecedented statistics over a wide energy range (~10MeV to ~100GeV). The PAMELA experiment consists of a permanent magnetic spectrometer, an electromagnetic calorimeter, a Time-of-Fight system, a neutron detector and a shower tail catcher. An anticoincidence (AC) system surrounds the spectrometer to detect particles which do not pass cleanly through the acceptance of the spectrometer. PAMELA will be mounted on a Russian Earth-observation satellite, and the launch is scheduled for 2006. The anticoincidence system for PAMELA has been developed by KTH, and consists of plastic scintillator detectors with photomultiplier tube read-out. Extensive testing has been performed during the development phase. Results are presented for environmental tests, tests with cosmic-rays and particle beams.</p><p>The design of the digital part of the AC electronics has been realised on an FPGA (Field Programmable Gate Array) and a DSP (Digital Signal Processor). It records signals from the 16 AC photomultipliers and from various sensors for over-current and temperature. It also provides functionality for setting the photomultiplier discrimination thresholds, system testing, issuing alarms and communication with the PAMELA main data acquisition system. The design philosophy and functionality needs to be reliable and suitable for use in a space environment.</p><p>To evaluate the performance of the AC detectors, a test utilizing cosmic-rays has been performed. The primary aim of the test was to calibrate the individual channels to gain knowledge of suitable discriminator levels for flight. A secondary aim was to estimate the AC detector efficiency. A lower limit of (99.89±0.04)% was obtained. An in-orbit simulation study was performed using protons to estimate trigger rates and investigate the AC system performance in a second level trigger. The average orbital trigger rate was estimated to be (8.4±0.6)Hz, consisting of (2.0±0.2)Hz good triggers and (6.4±0.5)Hz background. Inclusion of the AC system in the trigger condition to reduce background (for the purpose of data handling capacity) leads to losses of good triggers due to backscattering from the calorimeter (90% loss for 300GeV electrons and 25% for 100GeV protons). A method, using the calorimeter, for identifying backscattering events was investigated and found to reduce the loss of good events to below 1% (300GeV electrons) and 5% (100GeVn of 70%.</p>