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 annihilate. 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.
Highlights
Antihydrogen (H ) atoms were trapped in the ALPHA apparatus at CERN [1, 2]
A very few antiatoms are trapped at the end of the mixing cycle, and confined with these few are approximately 10,000–20,000 bare antiprotons. If these antiprotons were isotropically distributed in velocity, it is easy to show by integrating over the distribution that the fraction that would be trapped by the octupole and mirror fields alone once the electrostatic fields are turned off is:
If an antihydrogen atom is sufficiently excited that it can be ionized by the large electric field of strength Emax or less near the trap wall, it will always be ionized by passage through the magnetic field at the center of the trap where it is created if it is moving faster than approximately Emax/B0
Summary
Antihydrogen (H ) atoms were trapped in the ALPHA apparatus at CERN [1, 2]. The detector is sensitive only to the charged particles produced by antiproton annihilations; it cannot detect the gamma rays from positron annihilations It cannot directly discriminate between antihydrogen and any bare antiprotons that might be trapped. A very few antiatoms are trapped at the end of the mixing cycle, and confined with these few are approximately 10,000–20,000 bare antiprotons If these antiprotons were isotropically distributed in velocity, it is easy to show by integrating over the distribution that the fraction that would be trapped by the octupole and mirror fields alone once the electrostatic fields are turned off is:.
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
