Abstract
This study presents a further step within the ongoing R&D activities for the redesign of the CERN's Antiproton Decelerator Production Target (AD-Target). A first scaled target prototype, constituted of a sliced core made of ten Ta rods -8 mm diameter, 16 mm length- embedded in a compressed expanded graphite (EG) matrix, inserted in a 44 mm diameter Ti-6Al-4V container, has been built and tested under proton beam impacts at the CERN's HiRadMat facility, in the so called HRMT-42 experiment. This prototype has been designed following the lessons learned from previous numerical and experimental works (HRMT-27 experiment) aiming at answering the open questions left in these studies. Velocity data recorded on-line at the target periphery during the HRMT-42 experiment is presented, showing features of its dynamic response to proton beam impacts. Furthermore, x-ray and neutron tomographies of the target prototype after irradiation have been performed. These non-destructive techniques show the extensive plastic deformation of the Ta core, but suggest that the EG matrix can adapt to such deformation, which is a positive result. The neutron tomography successfully revealed the internal state of the tantalum core, showing the appearance of voids of several hundreds of micrometers, in particular in the downstream rods of the core. The possible origin of such voids is discussed while future microstructure analysis after the target opening will try to clarify their nature.
Highlights
Antiprotons are currently produced at CERN for the antiproton decelerator (AD) facility by impacting intense proton beams of 26 GeV=c onto a high-Z water-cooled target
A first scaled target prototype, constituted of a sliced core made of ten Ta rods −8 mm diameter, 16 mm length-embedded in a compressed expanded graphite (EG) matrix, inserted in a 44 mm diameter Ti-6Al-4V container, has been built and tested under proton beam impacts at the CERN’s HiRadMat facility, in the so called HRMT-42 experiment
The HRMT-42 experiment aimed at impacting around 50 high intensity proton pulses on the target presented in Fig. 1(a), which consists of ten Ta rods of 8 mm diameter, 16 mm length, embedded in a compressed EG matrix and SCALED PROTOTYPE OF A TANTALUM TARGET
Summary
Antiprotons are currently produced at CERN for the antiproton decelerator (AD) facility by impacting intense proton beams of 26 GeV=c onto a high-Z water-cooled target. These simulations showed that a maximum temperature rise of 2000 °C takes place in the target core in less than 0.5 μs (the duration of a pulse burst), as a consequence of the sudden deposition of energy by the primary proton beam This sudden rise of temperature leads to the excitation of a radial mode of vibration ( referred to as a radial wave), which exposes the material to oscillating compressive-to-tensile stresses of several gigapascals, well above its strength limit. The HRMT-27 experiment brought important insights, from a fundamental point of view, on the response of thin rods of high density materials dynamically loaded by the impact of short and intense proton pulses It left several open questions relevant for the design of an improved AD-Target. The current study shows the HRMT-42 target manufacturing procedure, experiment design, on-line results, and first post irradiation examination
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