CERN Accelerating science

Article
Report number	arXiv:1201.3944
Title	Discriminating between antihydrogen and mirror-trapped antiprotons in a minimum-B trap
Related title	Antihydrogen and mirror-trapped antiproton discrimination: Discriminating between antihydrogen and mirror-trapped antiprotons in a minimum-B trap
Author(s)	Amole, C (York U., Canada) ; Andresen, G B (Aarhus U.) ; Ashkezari, M D (Simon Fraser U.) ; Baquero-Ruiz, M (UC, Berkeley) ; Bertsche, W (Swansea U.) ; Butler, E (Swansea U. ; CERN) ; Cesar, C L (Rio de Janeiro Federal U.) ; Chapman, S (UC, Berkeley) ; Charlton, M (Swansea U.) ; Deller, A (Swansea U.) ; Eriksson, S (Swansea U.) ; Fajans, J (UC, Berkeley ; LBL, Berkeley) ; Friesen, T (Calgary U.) ; Fujiwara, M C (TRIUMF) ; Gill, D R (TRIUMF) ; Gutierrez, A (British Columbia U.) ; Hangst, J S (Aarhus U.) ; Hardy, W N (British Columbia U.) ; Hayden, M E (Simon Fraser U.) ; Humphries, A J (Swansea U.) ; Hydomako, R (Calgary U.) ; Kurchaninov, L (TRIUMF) ; Jonsell, S (Stockholm U.) ; Madsen, N (Swansea U.) ; Menary, S (York U., Canada) ; Nolan, P (Liverpool U.) ; Olchanski, K (TRIUMF) ; Olin, A (TRIUMF) ; Povilus, A (UC, Berkeley) ; Pusa, P (Liverpool U.) ; Robicheaux, F (Auburn U.) ; Sarid, E (Negev Nucl. Res. Ctr.) ; Silveira, D M (Rio de Janeiro Federal U.) ; So, C (UC, Berkeley) ; Storey, J W (TRIUMF) ; Thompson, R I (Calgary U.) ; van der Werf, D P (Swansea U.) ; Wurtele, J S (UC, Berkeley ; LBL, Berkeley)
Publication	2012
Imprint	20 Jan 2012
Number of pages	35
Note	Comments: 17 figures
In:	New J. Phys. 14 (2012) pp.105010
DOI	10.1088/1367-2630/14/1/015010 10.1088/1367-2630/14/1/015010.
Subject category	Other Fields of Physics
Accelerator/Facility, Experiment	CERN AD ; ALPHA AD-5
Abstract	Recently, antihydrogen atoms were trapped at CERN in a magnetic minimum (minimum-B) trap formed by superconducting octupole and mirror magnet coils. The trapped antiatoms were detected by rapidly turning off these magnets, thereby eliminating the magnetic minimum and releasing any antiatoms contained in the trap. Once released, these antiatoms quickly hit the trap wall, whereupon the positrons and antiprotons in the antiatoms annihilated. The antiproton annihilations produce easily detected signals; we used these signals to prove that we trapped antihydrogen. However, our technique could be confounded by mirror-trapped antiprotons, which would produce seemingly-identical annihilation signals upon hitting the trap wall. In this paper, we discuss possible sources of mirror-trapped antiprotons and show that antihydrogen and antiprotons can be readily distinguished, often with the aid of applied electric fields, by analyzing the annihilation locations and times. We further discuss the general properties of antiproton and antihydrogen trajectories in this magnetic geometry, and reconstruct the antihydrogen energy distribution from the measured annihilation time history.

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