G. Presser

Efficiency calibration of a Si(Li) detector at photon energies below 5 keV

Abstract A method is described for determining the photopeak efficiency of Si(Li) X-ray detectors in the energy range from 1 to 5 keV.

Radiative Auger effect in heavy atoms

Abstract Weak X-ray bands were observed for several elements from 20 Ca to 55 Cs at energies below the K α lines. This is the first evidence of K shell radiative Auger effect in heavy atoms. Relative intensities are compared for different K vacancy creation mechanisms.

Oxygen inducedK-shell ionization of selected elements from sulphur to bromine

K-shell X-ray production cross sections for oxygen ions on thin solid targets of 13 selected elements with atomic numbers between 16 and 35 were measured by a Si(Li) detector at incident ion energies from 7 to 24 MeV. Ionization cross sections are compared with calculations assuming Coulomb-ionization. Best agreement is found with theoretical cross sections that include corrections for binding energy and Coulomb deflection effects. Energy shifts ofKα andKβ X-rays andKα/Kβ intensity ratios were also measured and are used to deduce information about outer shell ionization.

K-shell ionization induced by 19F projectiles

Abstract We have measured K-shell ionization cross section of various elements in the region 16 ⩽ Z ⩽ 35 induced by 19 F projectiles. The results are compared with predictions of different Coulomb ionization theories.

A low pressure multiwire proportional chamber as a position sensitive detector of heavy ions: Construction and detection properties

Abstract A low pressure multiwire proportional chamber with two signal-wire planes and an active area of about 300 cm2 has been developed as particle detector in heavy-ion X-ray coincidence experiments to study the impact-parameter dependence of inner-shell ionization processes. The construction of the chamber and its detection properties concerning heavy ions with energies of E/A ≅ 0.1 to 1 MeV/u are described.

K-shell X-ray production for fluorine ions on target elements Ti to La

The production of target atomK-shell X-rays has been studied for 2 to 28 MeV fluorine ions incident on thin solid targets of 14 elements with atomic numbers Z2=22 to 57. Total X-ray production cross sections, energy shifts ofKα andKβ lines andKα/Kβ intensity ratios were measured with a Si(Li) detector. The results of cross section measurements are compared with theoretical predictions of inner shell ionization. In most cases, satisfactory agreement between measured cross sections and theoretical Coulomb ionization cross sections, corrected for the perturbation of the target atom by the projectile charge and for relativistic effects, was obtained.

Comparison of inner shell ionization by 16O and 18O projectiles

Abstract K-shell ionization induced by oxygen isotopes has been studied for several elements ranging from sulphur to bromine. Ionization cross sections and K α /K β intensity ratios are compared at equal projectile velocities.

Application of a low pressure proportional chamber in ion X-ray coincidence measurements

Abstract Heavy ion detection properties of a low pressure proportional chamber with 20 μm diam. wires and an effective area of 320 cm 2 are described. Investigations were made with He, Si, Cu and Ag ions in an energy range from 5.8 MeV to 30 MeV. The application of the chamber in an ion X-ray coincidence experiment is discussed.

Inner-shell ionization created by fluorine ions in nearly symmetric collisions

We have measured projectile and target X-ray cross sections for F + Si, S, Ar and Kr collisions at projectile energies from 1 to 25 MeV. The experiments were performed under single collision conditions using a differentially pumped gas target. X-rays were measured by a Si(Li) detector and a proportional counter. The experimental cross sections are compared to predictions of theoretical models for direct and quasi-molecular ionization. Effects of multiple ionization that influence theK-shell fluorescence yields were examined using experimental information from line energy shifts and intensity ratios.

Observation of two-electron-one-photon transitions in silicon☆

We report on the observation of Kαα X-rays of Si, produced in collisions of 15–28 MeV Si projectiles with various target atoms in the range Z = 6 to 29. Energy shifts of X-rays were measured and are compared with theoretical predictions. Cross section ratios for emission of Kαα and Kα radiation are given.