Penning trap
Penning traps are in use in many laboratories worldwide, including CERN, to store and investigate anti-particles such as antiprotons.
[2] The main advantages of Penning traps are the potentially long storage times and the existence of a multitude of techniques to manipulate and non-destructively detect the stored particles.
[3][4] This makes Penning traps versatile for the investigation of stored particles, but also for their selection, preparation or mere storage.
Dehmelt got inspiration from the vacuum gauge built by F. M. Penning where a current through a discharge tube in a magnetic field is proportional to the pressure.
Citing from H. Dehmelt's autobiography:[5] "I began to focus on the magnetron/Penning discharge geometry, which, in the Penning ion gauge, had caught my interest already at Göttingen and at Duke.
In their 1955 cyclotron resonance work on photoelectrons in vacuum Franken and Liebes had reported undesirable frequency shifts caused by accidental electron trapping.
Their analysis made me realize that in a pure electric quadrupole field the shift would not depend on the location of the electron in the trap.
In resistive cooling, moving image charges in the electrodes are made to do work through an external resistor, effectively removing energy from the ions.
Radiative cooling is the process by which the ions lose energy by creating electromagnetic waves by virtue of their acceleration in the magnetic field.
This process dominates the cooling of electrons in Penning traps, but is very small and usually negligible for heavier particles.
The signal is detected as an image current on a pair of plates which the packet of ions passes close to as they cyclotron.
The resulting signal is called a free induction decay (fid), transient or interferogram that consists of a superposition of sine waves.
A geonium atom is a pseudo-atomic system that consists of a single electron or ion stored in a Penning trap which is 'bound' to the remaining Earth, hence the term 'geonium'.
An inhomogeneous magnetic "bottle field" is applied to measure the quantum properties by the "continuous Stern-Gerlach" technique.
[citation needed] In November 2017, an international team of scientists isolated a single proton in a Penning trap in order to measure its magnetic moment to the highest precision to date.
