0000000000255739
AUTHOR
Peter Egelhof
Development of an array of calorimetric low-temperature detectors for heavy ion physics
Abstract Calorimetric low-temperature detectors have been investigated for several applications in heavy ion physics within the last 15 years. The detectors used consist of sapphire absorbers of 2×3×0.33 mm 3 and superconducting aluminum transition edge sensors operated at T ≈1.5 K. To fully exploit the potential of such detectors for heavy ion physics, a detector array is developed. For this purpose, a specially adapted 4 He bath cryostat with a base temperature of 1.2 K, which allows an active detector area of 30×80 mm 2 , was constructed. As different detectors have different transition temperatures, each detector pixel has to be adjusted to its specific working point and temperature sta…
First application of calorimetric low-temperature detectors in accelerator mass spectrometry
Abstract For the first time, calorimetric low-temperature detectors were applied in accelerator mass spectrometry, a well-known method for determination of very small isotope ratios with high sensitivity. The aim of the experiment was to determine with high accuracy the isotope ratio of 236U/238U for several samples of natural uranium, 236U being known as a sensitive monitor for neutron flux. Measurements were performed at the VERA tandem accelerator at Vienna, Austria. The detectors consist of sapphire absorbers and superconducting transition edge thermometers operated at T≈ 1.5 K. The relative energy resolution obtained for 17.39 MeV 238U is ΔE/E=4–9×10−3, depending on the experimental co…
Noise analysis for calorimetric low-temperature detectors for heavy ions
The energy resolution of calorimetric low-temperature detectors for heavy ions has been analyzed. It is shown that the contribution of base line noise is small. The energy resolution is determined by intrinsic fluctuations of the detector signal. An incomplete energy thermalization during the stopping process of the heavy ion, the dependence of signal shape on impact position and fluctuations of the Al-TES thermometer response are considered as main sources of detector line broadening. Test measurements with 5 MeV α-particles are presented.
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 Coulomb"elds, not accessible otherwise. For the investigation of the Lyman-a transitions in 208Pb81‘ or 238U91‘ with su$cient accuracy a high resolving calorimetric detector for hard X-rays (E)100 keV) is presently developed. The detector modules consist of arrays of silicon thermistors and of X-ray absorbers made of high Z material to optimize the absorption e$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. T…
Precise determination of the 1s Lamb Shift in hydrogen-like heavy ions at the ESR storage ring using microcalorimeters
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 measu…
The electronion scattering experiment ELISe at the International Facility for Antiproton and Ion Research (FAIR) - A conceptual design study
The electronion scattering experiment ELISe is part of the installations envisaged at the new experimental storage ring at the International Facility for Antiproton and Ion Research (FAIR) in Darmstadt, Germany. It offers an unique opportunity to use electrons as probe in investigations of the structure of exotic nuclei. The conceptual design and the scientific challenges of ELISe are presented. © 2011 Elsevier B.V. All rights reserved.
High-precision X-ray spectroscopy of highly-charged ions at the experimental storage ring using silicon microcalorimeters
Abstract X-ray spectroscopy on highly charged heavy ions provides a sensitive test of quantum electrodynamics in very strong Coulomb fields. One limitation of the current accuracy of such experiments is the energy resolution of available X-ray detectors for energies up to 100 keV. To improve this accuracy, a novel detector concept, namely the concept of microcalorimeters, is exploited for this kind of measurements. The microcalorimeters used in the present experiments consist of silicon thermometers, ensuring a high dynamic range, and of absorbers made of high-Z material to provide high X-ray absorption efficiency. Recently, besides an earlier used detector, a new compact detector design, h…
Isotopic distributions of thermal-neutron-induced fission fragments of near-symmetric fission of Pu239,241 determined using calorimetric low-temperature detectors
Isotopic distributions were measured for the light fragment group in the transition region from asymmetric to symmetric fission for thermal neutron induced fission of $^{239}\mathrm{Pu}$ and $^{241}\mathrm{Pu}$ using the novel technology of calorimetric low temperature detectors in combination with the passive absorber method. Nuclear charge distributions were determined for 24 masses in the range $A=89$ to $A=112$ for $^{241}\mathrm{Pu}({n}_{\mathrm{th}},f)$ for the first time with the LOHENGRIN mass spectrometer. Moving from asymmetric to symmetric fission, known data were supplemented for masses from $A=110$ to $A=112$ for $^{241}\mathrm{Pu}({n}_{\mathrm{th}},f)$ and from $A=109$ to $A=1…
Precise determination of the 1s Lamb shift in hydrogen-like lead and gold using microcalorimeters
Quantum electrodynamics in very strong Coulomb fields is one scope which has not yet been tested experimentally with suffcient accuracy to really determine whether the perturbative approach is valid. One sensitive test is the determination of the 1s Lamb Shift in highly-charged very heavy ions. The 1s Lamb Shift of hydrogen-like lead (Pb81+) and gold (Au78+) has been determined using the novel detector concept of silicon microcalorimeters for the detection of hard X-rays. The results of (260 +- 22) eV for lead and (208 +- 13) eV for gold are within error bars in good agreement with theoretical predictions. For hydrogen-like lead, this represents the most accurate determination of the 1s Lam…
Determination of electronic stopping powers of 0.05–1MeV/u 131Xe ions in C-, Ni- and Au-absorbers with calorimetric low temperature detectors
Abstract A new experimental system for precise determination of electronic stopping powers of heavy ions has been set up at the accelerator laboratory of the University of Jyvaskyla. The new setup, combining an established B-ToF system and an array of calorimetric low temperature detectors (CLTDs), has been used for the determination of electronic stopping powers of 0.05–1 MeV/u 131Xe ions in carbon, nickel and gold. Thereby advantage of the improved linearity and energy resolution of CLTDs as compared to the previously used ionization detector was taken to reduce energy calibration errors and to increase sensitivity for the energy loss determination, in particular at very low energies. The…
Experimental program of the Super-FRS Collaboration at FAIR and developments of related instrumentation
The physics program at the super-conducting fragment separator (Super-FRS) at FAIR, being operated in a multiple-stage, high-resolution spectrometer mode, is discussed. The Super-FRS will produce, separate and transport radioactive beams at high energies up to 1.5 AGeV, and it can be also used as a stand-alone experimental device together with ancillary detectors. Various combinations of the magnetic sections of the Super-FRS can be operated in dispersive, achromatic or dispersion-matched spectrometer ion-optical modes, which allow measurements of momentum distributions of secondary-reaction products with high resolution and precision. A number of unique experiments in atomic, nuclear and h…
High-precision x-ray spectroscopy of highly charged ions with microcalorimeters
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 experimental precision, the new detector concept of microcalorimeters is now exploited for such measurements. Such detectors consist of compensated-doped silicon thermistors and Pb or Sn absorbers to obtain high quantum efficiency in the energy range of 40–70 keV, where the Doppler-shifted Lyman lines are located. For the first time, a microcalorimeter was applied in an experiment to precisely determine the transition energy of the Lyman lines of lead ions at the experimental storage ring at GSI. T…
Quasi-free scattering with 6,8He beams
Abstract This paper presents the results of experimental investigations of ( p , p n ) , ( p , p α ) and ( p , p 6 He) reactions with relativistic 6 He and 8 He beams impinging on a hydrogen target. Information on the structure of extremely neutron-rich nuclei was obtained by using the unique characteristic of quasi-free scattering processes and inverse kinematics. For the first time, momentum distributions of complex clusters inside 6 He and 8 He were measured. Spectroscopic factors for valence neutrons, α - and 6 He clusters were deduced from the experimental data. They demonstrate that the filling of the p 1 2 shell is the essential feature of the 8 He structure. It is shown that the 8 H…