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AEGIS at CERN: Measuring Antihydrogen Fall  [PDF]
Marco G. Giammarchi
Physics , 2011, DOI: 10.1007/s00601-012-0439-6
Abstract: The main goal of the AEGIS experiment at the CERN Antiproton Decelerator is the test of fundamental laws such as the Weak Equivalence Principle (WEP) and CPT symmetry. In the first phase of AEGIS, a beam of antihydrogen will be formed whose fall in the gravitational field is measured in a Moire' deflectometer; this will constitute the first test of the WEP with antimatter.
Quantum ballistic experiment on antihydrogen fall  [PDF]
A. Yu. Voronin,V. V. Nesvizhevsky,G. Dufour,S. Reynaud
Physics , 2015,
Abstract: We study an interferometric approach to measure gravitational mass of antihydrogen. The method consists of preparing a coherent superposition of antihydrogen quantum state localized near a material surface in the gravitational field of the Earth, and then observing the time distribution of annihilation events followed after the free fall of an initially prepared superposition from a given height to the detector plate. We show that a corresponding time distribution is related to the momentum distribution in the initial state that allows its precise measurement. This approach is combined with a method of production of a coherent superposition of gravitational states by inducing a resonant transition using oscillating gradient magnetic field. We estimate an accuracy of measuring the gravitational mass of antihydrogen atom which could be deduced from such a measurement.
Prospects for studies of the free fall and gravitational quantum states of antimatter  [PDF]
Gabriel Dufour,David B. Cassidy,Paolo Crivelli,Pascal Debu,Astrid Lambrecht,Valery V. Nesvizhevsky,Serge Reynaud,Alexei Yu. Voronin,Thomas E. Wall
Physics , 2014, DOI: 10.1155/2015/379642.
Abstract: Different experiments are ongoing to measure the effect of gravity on cold neutral antimatter atoms such as positronium, muonium and antihydrogen. Among those, the project GBAR in CERN aims to measure precisely the gravitational fall of ultracold antihydrogen atoms. In the ultracold regime, the interaction of antihydrogen atoms with a surface is governed by the phenomenon of quantum reflection which results in bouncing of antihydrogen atoms on matter surfaces. This allows the application of a filtering scheme to increase the precision of the free fall measurement. In the ultimate limit of smallest vertical velocities, antihydrogen atoms are settled in gravitational quantum states in close analogy to ultracold neutrons (UCNs). Positronium is another neutral system involving antimatter for which free fall under gravity is currently being investigated at UCL. Building on the experimental techniques under development for the free fall measurement, gravitational quantum states could also be observed in positronium. In this contribution, we review the status of the ongoing experiments and discuss the prospects of observing gravitational quantum states of antimatter and their implications.
The Study of Neutrino Oscillations with Emulsion Detectors  [PDF]
A. Ereditato
Advances in High Energy Physics , 2013, DOI: 10.1155/2013/382172
Abstract: Particle detectors based on nuclear emulsions contributed to the history of physics with fundamental discoveries. The experiments benefited from the unsurpassed spatial and angular resolution of the devices in the measurement of ionizing particle tracks and in their identification. Despite the decline of the technique around the 1970’s caused by the development of the modern electronic particle detectors, emulsions are still alive today thanks to the vigorous rebirth of the technique that took place around the beginning of the 1990’s, in particular due to the needs of neutrino experiments. This progress involved both the emulsion detectors themselves and the automatic microscopes needed for their optical scanning. Nuclear emulsions have marked the study of neutrino physics, notably in relation to neutrino oscillation experiments and to the related first detection of tau-neutrinos. Relevant applications in this field are reviewed here with a focus on the main projects. An outlook is also given trying to address the main directions of the R&D effort currently in progress and the challenging applications to various fields. 1. Introduction to Nuclear Emulsions Particle detectors based on the nuclear emulsion technique contributed to the history of particle physics with fundamental discoveries and measurements that profited from their unsurpassed spatial and angular resolution in the measurement of charged elementary particle tracks. Moreover, thanks to specific detector arrangements, accurate momentum and energy measurements were also carried out. Despite the decline of the technique around 1960–1970 due to the development and use of the modern electronic particle detectors, emulsions are still used today, thanks to the vigorous rebirth of the technique that took place around the beginning of the 1990’s, driven by the needs of neutrino experiments. Nuclear emulsions have been effectively used in many particle physics experiments and in particular contributed to neutrino oscillation physics and to the related issue of the detection of tau-neutrinos ( ). Here, focus is on this specific physics subject and will unfortunately exclude the many scientific results that were obtained in other different fields. For those, we recommend the reader to consult existing reviews [1–3]. The reader is also invited to note that the emulsion detection technique is based on two independent aspects that have been synergic throughout their technological development: the emulsion detector itself and the devices (microscopes) necessary for extracting the information stored in the
A new application of emulsions to measure the gravitational force on antihydrogen  [PDF]
C. Amsler,A. Ariga,T. Ariga,S. Braccini,C. Canali,A. Ereditato,J. Kawada,M. Kimura,I. Kreslo,C. Pistillo,P. Scampoli,J. W. Storey
Physics , 2012, DOI: 10.1088/1748-0221/8/02/P02015
Abstract: We propose to build and operate a detector based on the emulsion film technology for the measurement of the gravitational acceleration on antimatter, to be performed by the AEgIS experiment (AD6) at CERN. The goal of AEgIS is to test the weak equivalence principle with a precision of 1% on the gravitational acceleration g by measuring the vertical position of the anni- hilation vertex of antihydrogen atoms after their free fall in a horizontal vacuum pipe. With the emulsion technology developed at the University of Bern we propose to improve the performance of AEgIS by exploiting the superior position resolution of emulsion films over other particle de- tectors. The idea is to use a new type of emulsion films, especially developed for applications in vacuum, to yield a spatial resolution of the order of one micron in the measurement of the sag of the antihydrogen atoms in the gravitational field. This is an order of magnitude better than what was planned in the original AEgIS proposal.
First results on proton radiography with nuclear emulsion detectors  [PDF]
S. Braccini,A. Ereditato,I. Kreslo,U. Moser,C. Pistillo,S. Studer,P. Scampoli,A. Coray,E. Pedroni
Physics , 2010, DOI: 10.1088/1748-0221/5/09/P09001
Abstract: We propose an innovative method for proton radiography based on nuclear emulsion film detectors, a technique in which images are obtained by measuring the position and the residual range of protons passing through the patient's body. For this purpose, nuclear emulsion films interleaved with tissue equivalent absorbers can be used to reconstruct proton tracks with very high accuracy. This is performed through a fully automated scanning procedure employing optical microscopy, routinely used in neutrino physics experiments. Proton radiography can be used in proton therapy to obtain direct information on the average tissue density for treatment planning optimization and to perform imaging with very low dose to the patient. The first prototype of a nuclear emulsion based detector has been conceived, constructed and tested with a therapeutic proton beam. The first promising experimental results have been obtained by imaging simple phantoms.
Why We Already Know that Antihydrogen is Almost Certainly NOT Going to Fall "Up"  [PDF]
Scott Menary
Physics , 2012,
Abstract: The ALPHA collaboration (of which I am a member) has made great strides recently in trapping antihydrogen and starting down the path of making spectroscopic measurements. The primary goal of the experiment is to test CPT invariance but there is also interest in testing another fundamental issue -- the gravitational interaction between matter and antimatter (the so-called question of "antigravity"). As well as the other antihydrogen trapping experiments -- ASACUSA and ATRAP -- there is also a new experiment in the Antiproton Decelerator hall at CERN called AEGIS which is dedicated to testing the gravitional interaction between antihydrogen and the Earth. It has been claimed in the literature that there "is no compelling evidence or theoretical reason to rule out such a difference (i.e., between $g$ and $\bar{g}$) at the 1% level." I argue in this short paper that bending of light by the sun provides a more stringent limit than this.
Antihydrogen  [PDF]
Ivan Schmidt
Physics , 1997, DOI: 10.1063/1.53213
Abstract: CERN announced in January 1996 the detection of the first eleven atoms of antimatter ever produced. The experiment was based on a method proposed earlier by S. Brodsky, C. Munger and I. Schmidt, and which furthermore predicted exactly the number of atoms that were detected for the particular conditions of the experiment. The study of antihydrogen affords science the opportunity to continue research on the symmetry between matter and antimatter. In this talk the importance of antihydrogen as a basic physical system is discussed. Different production methods that have been tried in the past are briefly presented, and the method that was used in the CERN experiment is analyzed in detail. It consists in producing antihydrogen by circulating a beam of an antiproton ring through an internal gas target. In the Coulomb field of a nucleus, an electron-positron pair is created, and antihydrogen will form when the positron is created in a bound rather that a continuum state about the antiproton. The theoretical calculation of the production cross section is presented in detail. A discussion of the detection systems used both in the CERN experiment and in another similar experiment that is right now underway at Fermilab are also given. Finally I present and discuss possible future experiments using antihydrogen, including the measurement of the antihydrogen Lamb shift.
Cooling antihydrogen ions for the free-fall experiment GBAR  [PDF]
Laurent Hilico,Jean-Philippe Karr,Albane Douillet,Paul Indelicato,Sebastian Wolf,Ferdinand Schmidt Kaler
Physics , 2014,
Abstract: We discuss an experimental approach allowing to prepare antihydrogen atoms for the GBAR experiment. We study the feasibility of all necessary experimental steps: The capture of incoming $\bar{\rm H}^+$ ions at keV energies in a deep linear RF trap, sympathetic cooling by laser cooled Be$^+$ ions, transfer to a miniaturized trap and Raman sideband cooling of an ion pair to the motional ground state, and further reducing the momentum of the wavepacket by adiabatic opening of the trap. For each step, we point out the experimental challenges and discuss the efficiency and characteristic times, showing that capture and cooling are possible within a few seconds.
Towards Antihydrogen Confinement with the ALPHA Antihydrogen Trap  [PDF]
M. C. Fujiwara,G. Andresen,W. Bertsche,A. Boston,P. D. Bowe,C. L. Cesar,S. Chapman,M. Charlton,M. Chartier,A. Deutsch,J. Fajans,R. Funakoshi,D. R. Gill,K. Gomberoff,J. S. Hangst,W. N. Hardy,R. S. Hayano,R. Hydomako,M. J. Jenkins,L. V. Jorgensen,L. Kurchaninov,N. Madsen,P. Nolan,K. Olchanski,A. Olin,R. D. Page,A. Povilus,F. Robicheaux,E. Sarid,D. M. Silveira,J. W. Storey,R. I. Thompson,D. P. van der Werf,J. S. Wurtele,Y. Yamazaki
Physics , 2007, DOI: 10.1007/s10751-007-9527-2
Abstract: ALPHA is an international project that has recently begun experimentation at CERN's Antiproton Decelerator (AD) facility. The primary goal of ALPHA is stable trapping of cold antihydrogen atoms with the ultimate goal of precise spectroscopic comparisons with hydrogen. We discuss the status of the ALPHA project and the prospects for antihydrogen trapping.
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