P. Egelhof

High resolution detection of energetic heavy ions with a calorimetric low temperature detector

Abstract A low temperature calorimeter with good energy resolution was developed for detection of energetic heavy ions. It consists of a doped germanium crystal as thermometer and a sapphire crystal as absorber, and is operated in a 4 He window cryostat at temperatures ranging from 1.3 to 2.0 K. For 2.38 GeV 209 Bi ions a relative energy resolution of ΔE E = 1.8 × 10 −3 was observed, most probably still limited by the energy spread of the incident ion beam.

Calorimetric low-temperature detectors for high resolution x-ray spectroscopy on stored highly stripped heavy ions

The precise determination of the Lamb shift in heavy hydrogen-like ions provides a sensitive test of QED in very strong Coulomb fields, not accessible otherwise, and has also the potential to deduce nuclear charge radii. A brief overview on the present status of such experiments, performed at the storage ring ESR at GSI Darmstadt, is given. For the investigation of the Lyman-α transitions in Au78+- or U91+- ions with improved accuracy a high resolving calorimetric low temperature detector for hard x-rays (E⩽100u200akeV) is presently developed. The detector modules consist of arrays of silicon thermistors and of x-ray absorbers made of high Z material to optimize the absorption efficiency. The detectors are housed in a specially designed 3He/4He dilution refrigerator which fits to the geometry of the ESR target. The detector performance presently achieved is already close to fulfill the demands of the Lamb shift experiment. For a prototype detector an energy resolution of ΔEFWHM=75u200aeV is obtained for 60 keV x-...

Low-temperature X-ray detectors for precise Lamb shift measurements on hydrogen-like heavy ions

The precise determination of the Lamb shift in heavy hydrogen-like ions provides a sensitive test of quantum electrodynamics in very strong Coulombelds, not accessible otherwise. For the investigation of the Lyman-a transitions in 208Pb81‘ or 238U91‘ with su

Energy sensitive detection of heavy ions with transition edge calorimeters

cient accuracy a high resolving calorimetric detector for hard X-rays (E)100 keV) is presently developed. The detector modules consist of arrays of silicon thermistors and of X-ray absorbers made of high Z material to optimize the absorption e

Precise determination of the 1s Lamb Shift in hydrogen-like heavy ions at the ESR storage ring using microcalorimeters

ciency. The detectors are housed in a specially designed 3He/4He dilution refrigerator with a side arm which ts to the geometry of the internal target of the storage ring ESR at GSI Darmstadt. The detector performance presently achieved is already close to fulll the demands of the Lamb shift experiment. For a prototype detector pixel with a 0.3 mm2]66 lm Sn absorber an energy resolution of *E FWHM 75 eV is obtained for 60 keV X-rays. ( 2000 Elsevier Science B.V. All rights reserved. 1. Motivation The precise experimental test of the theoretical predictions of quantum electrodynamics (QED) on corrections to the classical Coulomb interaction potential is still } at least for high Z systems } one of the outstanding and most challenging problems of atomic physics. In the hydrogen atom, or in hydrogen like ions, the QED corrections give rise to the so-called Lamb shift, which is a small deviation of the binding energies from those predicted by the relativistic Dirac}Coulomb energy (see Fig. 1). Whereas in light systems, where QED

Application of Calorimetric Low Temperature Detectors (CLTD’s) for Precise Stopping Power Measurements of Heavy Ions in Matter

Status and results of a research project are reported, which aims at developing calorimetric low temperature detectors for heavy ions. The special conditions for the detection of energetic heavy ions are discussed. The response of an aluminium transition edge calorimeter, operated at about1.5K, to the impact of heavy ions was investigated. The observed energy resolutions ΔE/E=3.9×10−3for5.9MeV/u208Pb-ions, ΔE/E=1.6×10−3for4.8MeV/u58Ni-ions and ΔE/E=4.3×10−3for100MeV/u20Ne-ions are most probably not yet limited by the intrinsic detector resolution. The present results already represent an improvement over conventional solid state detectors and ionization chambers.

Calorimetric Low-Temperature Detectors for X-Ray Spectroscopy on Trapped Highly-Charged Heavy Ions

The precise determination of the energy of the Lyman α1 and α2 lines in hydrogen-like heavy ions provides a sensitive test of quantum electrodynamics in very strong Coulomb fields. To improve the precision of such experiments, the new detector concept of microcalorimeters, which detect the temperature change of an absorber after an incoming particle or photon has deposited its energy as heat, is now exploited. The microcalorimeters for x-rays used in these experiments consist of arrays of silicon thermometers and x-ray absorbers made of high-Z material. With such detectors, a relative energy resolution of about 1 per mille is obtained in the energy regime of 50–100 keV. Two successful measurement campaigns to determine the 1s Lamb Shift in Pb81+ and Au78+ have been completed: a prototype array has been applied successfully for the determination of the 1s Lamb Shift of Pb81+ at the ESR storage ring at GSI in a first test experiment. Based on the results of this test, a full array with 32 pixels has been equipped and has recently been applied to determine the 1s Lamb Shift in Au78+ ions. The energy of the Lyman-α1 line agrees within error bars well with theoretical predictions. The obtained accuracy is already comparable to the best accuracy obtained with conventional germanium detectors for hydrogen-like uranium.