Discriminating between antihydrogen and mirror-trapped antiprotons in a minimum-B trap
Discriminating between antihydrogen and mirror-trapped antiprotons in a minimum-B trap
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DOI：
10.1088/1367-2630/14/1/015010
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发表时间：
2012-01-31
影响因子：
3.3
通讯作者：
Wurtele, J. S.
中科院分区：
文献类型：
--
作者：
Amole, C.;Andresen, G. B.;Wurtele, J. S.
最近，在欧洲核子研究中心，反氢原子被困在由超导八极子和镜像磁线圈形成的磁性最小（最小- b）陷阱中。捕获的反原子是通过快速关闭这些磁体来检测的，从而消除磁性最小值并释放陷阱中包含的任何反原子。一旦被释放，这些反原子就会迅速撞上陷阱壁，然后反原子中的正电子和反质子就会湮灭。反质子湮灭产生容易被探测到的信号；我们用这些信号来证明我们捕获了反氢。然而，我们的技术可能会被镜像捕获的反质子所迷惑，它们在撞击阱壁时会产生看似相同的湮灭信号。本文讨论了镜像捕获反质子的可能来源，并表明通过分析湮灭位置和时间，通常借助外加电场可以很容易地区分反氢和反质子。我们进一步讨论了这种磁几何中反质子和反氢轨迹的一般性质，并根据测量的湮灭时间历史重建了反氢能量的分布。
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.