8 research outputs found
Absolute fraction of emitted Ps determined by GEANT4 supported analysis of gamma spectra
The fraction of positronium (Ps) emitted from a surface of a germanium single
crystal at high temperature is usually assumed to approach unity at zero
positron implantation energy. In the experiment, however, the determination of
the absolute Ps fraction is not straight forward since recording a reference
spectrum with Ps formation remains demanding. We use GEANT4-simulated
detector responses to and radiation sources mimicking
positron and Ps annihilation inside the (coincidence) Doppler-broadening
spectrometer at NEPOMUC, FRM II, in order to derive a reliable value for the Ps
fraction reemitted from a Ge(100) target heated close to its melting point.
Analysis of the measured spectra by fitting the simulated spectra shows an
absolute value of maximum Ps formation, contradicting the
assumption
Investigation of positron/positronium converter targets at AEgIS (CERN). Master's Thesis
Literaturverzeichnis Seiten XVII-XIXenthÀlt Abstract in englischer und deutscher Sprach
A fiber detector to monitor ortho-Ps formation and decay
We describe a novel method to use a scintillating fiber detector similar to the Fast Annihilation Cryogenic Tracking (FACT) used at the antimatter experiment AEឥIS to monitor the presence of ortho-positronium. A single scintillating fiber was coupled to a photomultiplier tube and irradiated by flashes of about 6 Ă 106 gamma quanta with 511keV energy, produced by approximately 10ns long positron pulses. The results were used to demonstrate the ability to track the creation and annihilation of ortho-positronium atoms over time in cryogenic and highly magnetic environments by using the FACT detector as a âdigital calorimeterâ.We describe a novel method to use a scintillating fiber detector similar to the Fast Annihilation Cryogenic Tracking (FACT) used at the antimatter experiment AEIS to monitor the presence of ortho-positronium. A single scintillating fiber was coupled to a photomultiplier tube and irradiated by flashes of about 6 x 10 511 keV -rays produced by long positron pulses. The results were used to demonstrate the ability to track the creation and annihilation of ortho-positronium atoms over time in cryogenic and highly magnetic environments by using the FACT detector as a "digital calorimeter"
Toward a pulsed antihydrogen beam for WEP tests in AEgIS
The AEgÌ
IS collaboration at CERNâs AD produces antihydrogen atoms in the form of a pulsed, isotropic source with a precisely defined formation time. AEgÌ
IS has recently undergone major upgrades to fully benefit from the increased number of colder antiprotons provided by the new ELENA decelerator and to move toward forming a horizontal beam to directly investigate the influence of gravity on the HÌ
atoms, thereby probing the Weak Equivalence Principle for antimatter. This contribution gives an overview of these upgrades as well as subsequent results from the first beam times with ELENA
Antiproton tagging and vertex fitting in a Timepix3 detector
Studies of antimatter are important for understanding our universe at a fundamental level. There are still unsolved problems, such as the matter-antimatter asymmetry in the universe. The AEgIS experiment at CERN aims at measuring the gravitational fall of antihydrogen in order to determine the gravitational force on antimatter. The proposed method will make use of a position-sensitive detector to measure the annihilation point of antihydrogen. Such a detector must be able to tag the antiproton, measure its time of arrival and reconstruct its annihilation point with high precision in the vertical direction. This work explores a new method for tagging antiprotons and reconstructing their annihilation point. Antiprotons from the Antiproton Decelerator at CERN were used to obtain data on direct annihilations on the surface of a silicon pixel sensor with Timepix3 readout. These data were used to develop and verify a detector response model for annihilation of antiprotons in this detector. Using this model and the antiproton data it is shown that a tagging efficiency of 50± 10% and a vertical position resolution of 22 ± 0.5 Όm can be obtained
Antiproton tagging and vertex fitting in a Timepix3 detector
Studies of antimatter are important for understanding our universe at a fundamental level. There are still unsolved problems, such as the matter-antimatter asymmetry in the universe. The AEgIS experiment at CERN aims at measuring the gravitational fall of antihydrogen in order to determine the gravitational force on antimatter. The proposed method will make use of a position-sensitive detector to measure the annihilation point of antihydrogen. Such a detector must be able to tag the antiproton, measure its time of arrival and reconstruct its annihilation point with high precision in the vertical direction. This work explores a new method for tagging antiprotons and reconstructing their annihilation point. Antiprotons from the Antiproton Decelerator at CERN were used to obtain data on direct annihilations on the surface of a silicon pixel sensor with Timepix3 readout. These data were used to develop and verify a detector response model for annihilation of antiprotons in this detector. Using this model and the antiproton data it is shown that a tagging efficiency of 50± 10% and a vertical position resolution of 22 ± 0.5 Όm can be obtained
Positron Manipulation and Positronium Laser Excitation in AEgIS
International audienceProduction of antihydrogen by using the charge exchange reaction, as proposed by AEgIS (Antimatter Experiment: gravity, Interferometry, Spectroscopy), requires the formation of a dense cloud of positronium atoms excited to Rydberg states. In this work, the recent advances in AEgIS towards this result are described. Namely, the manipulation of positrons to produce bunches containing more than 10 particles and the laser excitation of positronium to Rydberg states, using n=3 as intermediate level, are presented