Abstract
Another target preparative technique was recently added to the Isotope Research Materials Laboratory's (IRML) capabilities for custom target fabrication. In support of super-heavy-ion physics experiments, methods and equipment were developed for the preparation of 248CmF3 deposits on carbon foils. The starting material was obtained as either a chloride or nitrate solution, converted to the flouride, and evaporated on carbon foil substrates. Deposits ranging from 40 to 570 μg/cm2 were prepared as a 12-mm-diam spot on 45- to 60-μg/cm2 self-supported carbon foils. The deposits were then overcoated with approximately 10 μg/cm2 of carbon to minimize contamination problems during target handling. The high cost of 248Cm ($100/μg) and its limited availability were the key constraints in the development of preparative technology beyond the inherent radioactivity of 248Cm.
| Original language | English |
|---|---|
| Pages (from-to) | 15-20 |
| Number of pages | 6 |
| Journal | Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment |
| Volume | 257 |
| Issue number | 1 |
| DOIs | |
| State | Published - Jun 1 1987 |
Funding
Target characteristics are one of the major limiting factors in the study of super-heavy atomic systems. The specific example considered here is the preparation of 24sCm targets on carbon backings for bombardment by 232Th ions. Among the requirements placed on these targets are high density, uniformity, purity, and a thin substrate that will not interfere in nuclear measurements but will withstand bombardment by a heavy-ion beam. Attaining these goals is complicated by the scarcity of the target isotope and problems associated with handling small quantities of material and fragile substrates while taking the precautions appropriate for this curium isotope. Previously, targets of this type were prepared by electrodeposition or by evaporation of the fluoride onto aluminum or beryllium substrates. Electrodeposition generally produces a deposit of low density and can be difficult to perform on carbon substrates . Evaporation of the fluoride provides a dense deposit, but the beryllium or aluminum substrates can interfere in critical measurements . In support of experiments being conducted at Gesellschaft fiir Schwerionenforschung (GSI), Darmstadt, FRG, the IRML at the Oak Ridge National Laboratory (ORNL) undertook the preparation of 248 CmF3 targets by evaporation onto carbon foils. Processing techniques were developed and applied to prepare 12 mm diam 248CmF3 evaporated deposits on 45 to 60 hg/cm2 carbon backings supplied by GSI. The * Research sponsored by the Division of Basic Energy Scien-ces and Division of Nuclear Sciences, US Department of Energy, under contract DE-AC05-84OR21400 with the Martin Marietta Energy Systems, Inc.
| Funders | Funder number |
|---|---|
| Division of Basic Energy Scien-ces and Division of Nuclear Sciences | |
| U.S. Department of Energy | DE-AC05-84OR21400 |