TY - JOUR
T1 - Pumped helium system for cooling positron and electron traps to 1.2 K
AU - Wrubel, J.
AU - Gabrielse, G.
AU - Kolthammer, W. S.
AU - Larochelle, P.
AU - Mcconnell, R.
AU - Richerme, P.
AU - Grzonka, D.
AU - Oelert, W.
AU - Sefzick, T.
AU - Zielinski, M.
AU - Borbely, J. S.
AU - George, M. C.
AU - Hessels, E. A.
AU - Storry, C. H.
AU - Weel, M.
AU - Müllers, A.
AU - Walz, J.
AU - Speck, A.
N1 - Funding Information:
This work is primarily supported by the NSF and AFOSR of the US. Other support for ATRAP is from the BMBF, DFG, and DAAD of Germany, along with the NSERC, CRC, CFI and OIT of Canada. W.O. was supported in part by CERN. Thanks to I. Silvera for useful comments on the manuscript.
PY - 2011/6/1
Y1 - 2011/6/1
N2 - Extremely precise tests of fundamental particle symmetries should be possible via laser spectroscopy of trapped antihydrogen (H) atoms. H atoms that can be trapped must have an energy in temperature units that is below 0.5 K - the energy depth of the deepest magnetic traps that can currently be constructed with high currents and superconducting technology. The number of atoms in a Boltzmann distribution with energies lower than this trap depth depends sharply upon the temperature of the thermal distribution. For example, ten times more atoms with energies low enough to be trapped are in a thermal distribution at a temperature of 1.2 K than for a temperature of 4.2 K. To date, H atoms have only been produced within traps whose electrode temperature is 4.2 K or higher. A lower temperature apparatus is desirable if usable numbers of atoms that can be trapped are to eventually be produced. This report is about the pumped helium apparatus that cooled the trap electrodes of an H apparatus to 1.2 K for the first time. Significant apparatus challenges include the need to cool a 0.8 m stack of 37 trap electrodes separated by only a mm from the substantial mass of a 4.2 K Ioffe trap and the substantial mass of a 4.2 K solenoid. Access to the interior of the cold electrodes must be maintained for antiprotons, positrons, electrons and lasers.
AB - Extremely precise tests of fundamental particle symmetries should be possible via laser spectroscopy of trapped antihydrogen (H) atoms. H atoms that can be trapped must have an energy in temperature units that is below 0.5 K - the energy depth of the deepest magnetic traps that can currently be constructed with high currents and superconducting technology. The number of atoms in a Boltzmann distribution with energies lower than this trap depth depends sharply upon the temperature of the thermal distribution. For example, ten times more atoms with energies low enough to be trapped are in a thermal distribution at a temperature of 1.2 K than for a temperature of 4.2 K. To date, H atoms have only been produced within traps whose electrode temperature is 4.2 K or higher. A lower temperature apparatus is desirable if usable numbers of atoms that can be trapped are to eventually be produced. This report is about the pumped helium apparatus that cooled the trap electrodes of an H apparatus to 1.2 K for the first time. Significant apparatus challenges include the need to cool a 0.8 m stack of 37 trap electrodes separated by only a mm from the substantial mass of a 4.2 K Ioffe trap and the substantial mass of a 4.2 K solenoid. Access to the interior of the cold electrodes must be maintained for antiprotons, positrons, electrons and lasers.
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U2 - 10.1016/j.nima.2011.01.030
DO - 10.1016/j.nima.2011.01.030
M3 - Article
AN - SCOPUS:79955719188
VL - 640
SP - 232
EP - 240
JO - Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment
JF - Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment
SN - 0168-9002
IS - 1
ER -