This report concerns a detection module used for a pellet tracking system. Spheres of frozen hydrogen known as pellets can be used as internal targets in hadron physics experiments. Pellets are created some distance above the accelerator beam and directed in a pellet beam pipe to intersect the accelerator beam. To determine the position of a pellet in the interaction region in the case of an interaction, the pellets need to be tracked. This is done using tracking sections along the pellet beam pipe with measurement levels containing lasers illuminating the pellets and cameras, detecting the light. The pellet position in the interaction region can be reconstructed with an accuracy of 0.1 mm. To reach this accuracy there are high demands on the alignment of the cameras and lasers. Alignment by a pellet beam pipe is generally difficult so a solution enabling alignment elsewhere is desired. Therefore a detection module consisting of a plate with cameras and lasers mounted to it has been constructed. These cameras and lasers can be aligned in an alignment bench setup before being transported to a pellet beam pipe. The alignment of the cameras and lasers on the detection module must be maintained under certain conditions e.g. transportation, temperature changes, exposure to vibrations. This report covers investigations regarding the mechanical stability of the detection module under these conditions. Different alignment bench targets are investigated. The effects of the optics of the cameras and lasers and the functionality of the detection module are investigated.

The development of a system for optical tracking of frozen hydrogen microsphere targets (pellets) was done. It is intended for the upcoming hadron physics experiment PANDA at FAIR, Darmstadt, Germany. Knowledge of the interaction position, obtained with this system, will improve background rejection, precision of particle track reconstruction and will also help distinguish between primary and secondary vertices. Investigations of pellet detection conditions and pellet stream parameters were performed at Uppsala Pellet Test Station located at The Svedberg Laboratory. Various illumination and detection conditions were checked and optimized. The gained knowledge has been used to develop Monte Carlo procedures simulating experiments with pellets. Then simulations of pellet tracking were carried out including the constraints from the PANDA setup. The performance of the tracking was checked for various pellet stream and pellet detection conditions. Two procedures of pellet track reconstruction were developed – a fast procedure and a high efficiency procedure. The studies were done for one tracking section (just below pellet generator) and for two sections (the second just above pellet dump) and showed that the resolution of the tracking system can be better than 100 μm (sigma) in each direction and that the interaction point will be reconstructed for 70-95% of hadronic events, for suitable pellet stream and detection conditions. Usage of pellet tracking information in the hadronic data analysis was discussed, concerning the data taking, particle track reconstruction together with the PANDA micro vertex detector, hadronic event classification and treatment of the various classes. Test measurements with the WASA setup at FZJ, Jülich, Germany were done to check how the information about the number of pellets in the accelerator beam region can be used in the hadronic data analysis. Instantaneous rates of WASA "elastic" triggers were used for classification of hadronic events as coming from pellets or from a background. The study clearly showed that one can distinguish between the two event classes. The study gave experience in using two different systems synchronized with each other – the experiment's DAQ and another system that works with a much longer time scale – similar to the pellet tracking system. / Ett system för optisk spårning av frysta mikrosfärer av väte (pelletar) har utvecklats för användning i det kommande hadronfysikexperimentet PANDA vid FAIR, Darmstadt i Tyskland. Kunskapen om positionen för växelverkan som fås med hjälp av detta system kommer att förbättra möjligheten att diskriminera mot bakgrund, att öka precisionen i partikelspårsrekonstruktionen och kommer också att hjälpa till att skilja mellan primära och sekundära växelverkanspunkter. Undersökningar av pelletdetektionsmöjligheter och pelletströmmens egenskaper har gjorts vid Uppsala Pellet Test Station vid The Svedberglaboratoriet. Olika belysnings och detektionsvillkor har testats och optimerats. Den erhållna kunskapen har använts för att utveckla en Monte-Carlo procedur för att kunna simulera de olika experimenten med pelletar. Därefter genomfördes simuleringar av förväntade pelletspårningsprestanda för PANDA uppställningen. Prestanda och upplösning av spårningen kontrollerades för olika pelletsström och detektionsförhållanden. Två procedurer för spårrekonstruktion utvecklades för studien – en snabbare och en med högsta möjliga effektivitet. Den kommer att kunna användas i dataanalysen när fullskalig pelletspårning används ihop med ett partikeldetektorsystem. Studien gjordes för två fall, dels för en spårningssektion (placerad just under pelletgeneratorn) och dels med ytterligare en sektion (placerad just ovanför pelletdumpen). Studien visade att positionsupplösningen som förväntas från spårningssystemet är bättre än 100 μm (sigma) i varje riktning och att växelverkanspunkten kan rekonstrueras för 70-95% av de hadroniska händelserna, för lämpliga pelletströms- och detektionsvillkor. Användningen av pelletspårningsinformationen i analysen av hadroniska händelsedata diskuterades m.a.p. datainsamling, m.a.p. partikelspårsrekonstruktion ihop med PANDA's mikrovertexdetektor och m.a.p. klassificering av händelser. Det gjordes testmätningar med WASA-uppställningen vid FZJ, Jülich i Tyskland för att se hur informationen om antalet pelletar i acceleratorstrålområdet kan användas i experimentets dataanalys. Den momentana frekvensen av elastiska spridningshändelser användes för en grov klassificering av händelsers ursprung såsom varande antingen från en pellet eller från någon källa till bakgrund. Studien visade klart att man kan skilja de båda klasserna åt. Studien gav också erfarenhet av hur man kan använda två synkroniserade datasystem – experimentets datainsamlingssystem och ett annat system som arbetar med en mycket längre tidsskala – liknande pelletspårningssystemets. / Wykonane zostały prace nad rozwojem systemu pozwalającego na optyczne śledzenie zamarzniętych wodorowych mikrokulek (pelletów). System przeznaczony jest do zastosowania w planowanym eksperymencie z dziedziny fizyki hadronowej, PANDA (FAIR, Darmstadt, Niemcy). Wiedza o położeniu punktu interakcji, uzyskana dzięki temu systemowi, poprawi redukcję tła, precyzję rekonstrukcji torów cząstek, a także pomoże w rozróżnianiu pierwotnych i wtórnych wierzchołków interakcji. Na Uppsalskiej Stacji Pelletowej (Uppsala Pellet Test Station) umieszczonej w Laboratorium The Svedberga, przeprowadzone zostały badania warunków detekcji pelletów i parametrów strumienia pelletowego. Różne warunki oświetlenia oraz detekcji pelletów zostały sprawdzone i zoptymalizowane. Uzyskana wiedza została użyta do stworzenia procedur Monte Carlo symulujących eksperymenty z pelletami. W następnym kroku przeprowadzone zostały symulacje śledzenia pelletów biorące pod uwagę więzy narzucone przez konstrukcję systemu PANDA. Wydajność systemu sprawdzona została dla różnych warunków strumienia pelletowego i detekcji pelletów. Stworzone zostały dwie procedury rekonstrukcji torów pelletowych -- procedura szybka i procedura wysokoefektywna. Badania przeprowadzone zostały dla jednej sekcji śledzącej (bezpośrednio poniżej generatora pelletów) oraz dla dwóch sekcji (druga bezpośrednio nad miejscem zbierania pelletów) i pokazały, że rozdzielczość systemu śledzenia może być lepsza niż 100 μm (sigma) w każdym z kierunków oraz że punkt interakcji będzie zrekonstruowany dla 70-95\% zdarzeń hadronowych, dla odpowiednich warunków strumienia pelletów i warunków detekcji. Użycie informacji ze śledzenia pelletów w analizie danych hadronowych zostało przedyskutowane uwzględniając proces zbierania danych, rekonstrukcję torów cząstek we współpracy z mikrodetektorem wierzchołków systemu PANDA, klasyfikację zdarzeń hadronowych oraz sposób traktowania różnych klas zdarzeń. Pomiary testowe z użyciem detektora WASA (FZJ, Jülich, Niemcy) zostały dokonane w celu sprawdzenia jak informacja o liczbie pelletów w obszarze wiązki może zostać użyta w analizie danych hadronowych. Chwilowe częstotliwości "elastycznych" triggerów systemu WASA zostały użyte w celu klasyfikacji zdarzeń hadronowych jako pochodzących z interakcji wiązka-pellet lub wiązka-tło. Badania wykazały iż możliwe jest rozróżnienie między tymi dwoma klasami zdarzeń. Uzyskano również doświadczenie w używaniu dwóch różnych systemów zsynchronizowanych ze sobą – eksperymentalnego systemu zbierania danych oraz innego systemu, działającego w znacznie dłuższej skali czasowej – podobnie do systemu śledzenia pelletów.

Within the PANDA experiment, proton anti-proton collisions will be studied in order to gain knowledge about the strong interaction. One interesting aspect is the production and decay of charmed hadrons. The charm quark is three orders of magnitude heavier than the light up- and down-quarks which constitue the matter we consist of. The detection of charmed particles is a challenge since they are rare and often hidden in a large background. There will be three different targets used at the experiment; the cluster-jet, the untracked pellet and the tracked pellet. All three targets meet the experimental requirements of high luminosity. However they have different properties, concerning the effect on beam quality and the determination of the interaction point. In this thesis, simulations and reconstruction of the charmed D-mesons using the three different targets have been made. The data quality, such as momentum resolution and vertex resolution has been studied, as well as how the different targets effect the reconstruction efficiency of D-meson have been analysed. The results are consistent with the results from a similar study in 2006, but provide additional information since it takes the detector response into account. Furthermore, a new target distribution have been implemented in the software package. This is the first results obtained from a cylindrical target distribution. The results are very important for PANDA since they show the limitations of different target types regarding the possibilities to reduce background. Simulations with the new target distribution have been made for all three targets and the results are presented.

<p>The PANDA experiment is a part of the future FAIR accelerator facility and will study the strong interaction by detecting the reaction products from antiproton-proton annihilations in a near full solid-angle configuration. One option for the internal proton target in PANDA is frozen micro-spheres of hydrogen, so-called pellets.</p><p>Such a pellet target is interesting because of the unique characteristics it offers; the high target thickness, the small interaction volume, the minimal gas load on the vacuum system, and the possibility of tracking individual pellets. Nevertheless, it is possible to allocate the bulky equipment needed to produce the pellets at a few meters away from the beam. This way particle detectors can be located close and almost fully around the interaction point.</p><p>This thesis is devoted to the optimization of a pellet target. To perform measurements, a Pellet-Test Station was built at The Svedberg Laboratory, Uppsala. For the first time, experimental results show the pellet distribution in space and time, and in addition, the vacuum along the pellet pipes. Furthermore, dedicated measurements carried out at CELSIUS/WASA demonstrate the existence of pellet heating as a result of beam-target interactions.</p><p>In performing calculations, the potential problems with pellet heating at PANDA are outlined. Moreover, to look at the consequences for the desired physics, a reaction involving short-lived D-mesons has been used to show the advantages of pellets compared to a more spacious target.</p><p>In conclusion, these studies lead to a deeper understanding of the pellet properties, which makes it possible to suggest future improvements, such as cooling with no vibrations.</p>

The PANDA experiment is a part of the future FAIR accelerator facility and will study the strong interaction by detecting the reaction products from antiproton-proton annihilations in a near full solid-angle configuration. One option for the internal proton target in PANDA is frozen micro-spheres of hydrogen, so-called pellets. Such a pellet target is interesting because of the unique characteristics it offers; the high target thickness, the small interaction volume, the minimal gas load on the vacuum system, and the possibility of tracking individual pellets. Nevertheless, it is possible to allocate the bulky equipment needed to produce the pellets at a few meters away from the beam. This way particle detectors can be located close and almost fully around the interaction point. This thesis is devoted to the optimization of a pellet target. To perform measurements, a Pellet-Test Station was built at The Svedberg Laboratory, Uppsala. For the first time, experimental results show the pellet distribution in space and time, and in addition, the vacuum along the pellet pipes. Furthermore, dedicated measurements carried out at CELSIUS/WASA demonstrate the existence of pellet heating as a result of beam-target interactions. In performing calculations, the potential problems with pellet heating at PANDA are outlined. Moreover, to look at the consequences for the desired physics, a reaction involving short-lived D-mesons has been used to show the advantages of pellets compared to a more spacious target. In conclusion, these studies lead to a deeper understanding of the pellet properties, which makes it possible to suggest future improvements, such as cooling with no vibrations.