Design of a high power production target for the Beam Dump Facility at CERN

The Beam Dump Facility (BDF) project is a proposed general-purpose facility at CERN, dedicated to beam dump and fixed target experiments. In its initial phase, the facility is foreseen to be exploited by the Search for Hidden Particles (SHiP) experiment. Physics requirements call for a pulsed 400 GeV/c proton beam as well as the highest possible number of protons on target (POT) each year of operation, in order to search for feebly interacting particles. The target/dump assembly lies at the heart of the facility, with the aim of safely absorbing the full high intensity Super Proton Synchrotron (SPS) beam, while maximizing the production of charmed and beauty mesons. High-Z materials are required for the target/dump, in order to have the shortest possible absorber and reduce muon background for the downstream experiment. The high average power deposited on target (305 kW) creates a challenge for heat removal. During the BDF facility Comprehensive Design Study (CDS), launched by CERN in 2016, extensive studies have been carried out in order to define and assess the target assembly design. These studies are described in the present contribution, which details the proposed design of the BDF production target, as well as the material selection process and the optimization of the target configuration and beam dilution. One of the specific challenges and novelty of this work is the need to consider new target materials, such as a molybdenum alloy (TZM) as core absorbing material and Ta2.5W as cladding. Thermo-structural and fluid dynamics calculations have been performed to evaluate the reliability of the target and its cooling system under beam operation. In the framework of the target comprehensive design, a preliminary mechanical design of the full target assembly has also been carried out, assessing the feasibility of the whole target system.Comment: 17 pages, 18 figure

Development of sputtered Nb3_{3}Sn films on copper substrates for superconducting radio-frequency applications

Superconducting radiofrequency (SRF) cavities that could provide a higher quality factor as well as a higher operational accelerating gradient at an affordable cost are highly demanded for future generation of particle accelerators. This study aims to demonstrate the potential of Nb$_3$Sn as material of choice for such SRF applications. Due to its brittle nature, the only way to produce an Nb$_3$Sn SFR cavity is to synthesise a thin layer inside a cavity made of niobium or copper. In this work, direct current magnetron sputtering (DCMS) using a stoichiometric target of Nb$_3$Sn was employed to produce films on copper samples. Assessment of the morphology, microstructure and superconducting properties were performed in order to ensure that this approach is suitable for SRF applications. The potential of the method is proven by obtaining films, which exhibit a crack-free surface, dense morphology and critical temperatures ($T_c$) up to 16K. The essential properties of the films have also been investigated with respect to the deposition and annealing conditions. The use of krypton as working gas during deposition increases the atomic percent of Sn in the film compared to argon. However, in contrast to argon, higher krypton pressures reduce the atomic percent of Sn. It was also found that long-lasting high temperature annealing leads to higher superconducting critical temperatures due to an increased crystallographic order. Particular attention was given to the influence of the copper substrate on the film growth as well as the microstructural and superconducting characteristics. We discuss the main constraints introduced by the copper substrate, such as copper interdiffusion during annealing, lattice mismatch and difference in thermal expansion coefficients and methods to overcome them.Superconducting radiofrequency (SRF) cavities that could provide a higher quality factor as well as a higher operational accelerating gradient at an affordable cost are in high demand for the future generation of particle accelerators. This study aims to demonstrate the potential of Nb3Sn as material of choice for such SRF applications. Due to its brittle nature, the only way to produce an Nb3Sn SFR cavity is to synthesise a thin layer inside a cavity made of niobium or copper. In this work, direct current magnetron sputtering using a stoichiometric target of Nb3Sn was employed to produce films on copper samples. Assessment of the morphology, microstructure and superconducting properties were performed in order to ensure that this approach is suitable for SRF applications. The potential of the method is proven by obtaining films, which exhibit a crack-free surface, dense morphology and critical temperatures (T c) up to 16 K. The essential properties of the films have also been investigated with respect to the deposition and annealing conditions. The use of krypton as working gas during deposition increases the atomic percent of Sn in the film compared to argon. However, in contrast to argon, higher krypton pressures reduce the atomic percent of Sn. It was also found that long-lasting high-temperature annealing leads to higher superconducting critical temperatures due to an increased crystallographic order. Particular attention was given to the influence of the copper substrate on the film growth as well as the microstructural and superconducting characteristics. We discuss the main constraints introduced by the copper substrate, such as copper interdiffusion during annealing, lattice mismatch and difference in thermal expansion coefficients and methods to overcome them

Hot isostatic pressing assisted diffusion bonding for application to the Super Proton Synchrotron internal beam dump at CERN

The new generation internal beam dump of the Super Proton Synchrotron (SPS) at CERN will have to dissipate approximately 270 kW of thermal power, deposited by the primary proton beam. For this purpose, it is essential that the cooling system features a very efficient heat evacuation. Diffusion bonding assisted by hot isostatic pressing (HIP) was identified as a promising method of joining the cooling circuits and the materials of the dumps core in order to maximize the heat transfer efficiency. This paper presents the investigation of HIP assisted diffusion bonding between two CuCr1Zr blanks enclosing SS 316L tubes and the realization of a real size prototype of one of the dump’s cooling plates, as well as the assessments of its cooling performance under the dump’s most critical operational scenarios. Energy-dispersive x-ray spectroscopy, microstructural analyses, measurements of thermal conductivity, and mechanical strength were performed to characterize the HIP diffusion bonded interfaces (CuCr1Zr-CuCr1Zr and CuCr1Zr-SS 316L). A test bench allowed to assess the cooling performance of the real size prototype. At the bonded interface, the presence of typical diffusional phenomena was observed. Moreover, measured tensile strength and thermal conductivity were at least equivalent to the lowest ones of the materials assembled and comparable to its bulk properties, meaning that a good bonding quality was achieved. Finally, the real size prototype was successfully tested with an ad hoc thermal test bench and with the highest operational thermal power expected in the new generation SPS internal beam dump. These results demonstrated the possibility to use HIP as a manufacturing technique for the cooling plates of the new generation SPS internal beam dump, but they also open up the way for further investigations on its exploitability to improve the cooling performance of any future high intensity beam intercepting device or in general devices requiring very efficient heat evacuation systemsThe new generation internal beam dump of the Super Proton Synchrotron (SPS) at CERN will have to dissipate approximately 270 kW of thermal power, deposited by the primary proton beam. For this purpose, it is essential that the cooling system features a very efficient heat evacuation. Diffusion bonding assisted by hot isostatic pressing (HIP) was identified as a promising method of joining the cooling circuits and the materials of the dumps core in order to maximize the heat transfer efficiency. This paper presents the investigation of HIP assisted diffusion bonding between two CuCr1Zr blanks enclosing SS 316L tubes and the realization of a real size prototype of one of the dump’s cooling plates, as well as the assessments of its cooling performance under the dump’s most critical operational scenarios. Energy-dispersive x-ray spectroscopy, microstructural analyses, measurements of thermal conductivity, and mechanical strength were performed to characterize the HIP diffusion bonded interfaces (CuCr1Zr-CuCr1Zr and CuCr1Zr-SS 316L). A test bench allowed to assess the cooling performance of the real size prototype. At the bonded interface, the presence of typical diffusional phenomena was observed. Moreover, measured tensile strength and thermal conductivity were at least equivalent to the lowest ones of the materials assembled and comparable to its bulk properties, meaning that a good bonding quality was achieved. Finally, the real size prototype was successfully tested with an ad hoc thermal test bench and with the highest operational thermal power expected in the new generation SPS internal beam dump. These results demonstrated the possibility to use HIP as a manufacturing technique for the cooling plates of the new generation SPS internal beam dump, but they also open up the way for further investigations on its exploitability to improve the cooling performance of any future high intensity beam intercepting device or in general devices requiring very efficient heat evacuation systems.The new generation internal beam dump of the Super Proton Synchrotron (SPS) at CERN will have to dissipate approximately 270 kW of thermal power, deposited by the primary proton beam. For this purpose, it is essential that the cooling system features a very efficient heat evacuation. Diffusion bonding assisted by Hot Isostatic Pressing (HIP) was identified as a promising method of joining the cooling circuits and the materials of the dump's core in order to maximise the heat transfer efficiency. This paper presents the investigation of HIP assisted diffusion bonding between two CuCr1Zr blanks enclosing SS 316L tubes and the realisation of a real size prototype of one of the dump's cooling plate, as well as the assessments of its cooling performance under the dumps most critical operational scenarios. Energy-dispersive X-ray (EDX) spectroscopy, microstructural analyses, measurements of thermal conductivity and mechanical strength were performed to characterize the HIP diffusion bonded interfaces (CuCr1Zr-CuCr1Zr and CuCr1Zr-SS316L). A test bench allowed to assess the cooling performance of the real size prototype. At the bonded interface, the presence of typical diffusional phenomena was observed. Moreover, measured tensile strength and thermal conductivity were at least equivalent to the lowest ones of the materials assembled and comparable to its bulk properties, meaning that a good bonding quality was achieved. Finally, the real size prototype was successfully tested with an ad-hoc thermal test bench and with the highest operational thermal power expected in the new generation SPS internal beam dump

Beam impact tests of a prototype target for the Beam Dump Facility at CERN: experimental setup and preliminary analysis of the online results

The Beam Dump Facility (BDF) is a project for a new facility at CERN dedicated to high intensity beam dump and fixed target experiments. Currently in its design phase, the first aim of the facility is to search for Light Dark Matter and Hidden Sector models with the Search for Hidden Particles (SHiP) experiment. At the core of the facility sits a dense target/dump, whose function is to absorb safely the 400 GeV/c Super Proton Synchrotron (SPS) beam and to maximize the production of charm and beauty mesons. An average power of 300 kW will be deposited on the target, which will be subjected to unprecedented conditions in terms of temperature, structural loads and irradiation. In order to provide a representative validation of the target design, a prototype target has been designed, manufactured and tested under the SPS fixed-target proton beam during 2018, up to an average beam power of 50 kW, corresponding to 350 kJ per pulse. The present contribution details the target prototype design and experimental setup, as well as a first evaluation of the measurements performed during beam irradiation. The analysis of the collected data suggests that a representative reproduction of the operational conditions of the Beam Dump Facility target was achieved during the prototype tests, which will be complemented by a Post Irradiation Examination campaign during 2020.The beam dump facility (BDF) is a project for a new facility at CERN dedicated to high intensity beam dump and fixed target experiments. Currently in its design phase, the first aim of the facility is to search for light dark matter and hidden sector models with the Search for Hidden Particles (SHiP) experiment. At the core of the facility sits a dense target/dump, whose function is to absorb safely the 400  GeV/c Super Proton Synchrotron (SPS) beam and to maximize the production of charm and beauty mesons. An average power of 300 kW will be deposited on the target, which will be subjected to unprecedented conditions in terms of temperature, structural loads and irradiation. In order to provide a representative validation of the target design, a prototype target has been designed, manufactured, and tested under the SPS fixed-target proton beam during 2018, up to an average beam power of 50 kW, corresponding to 350 kJ per pulse. The present contribution details the target prototype design and experimental setup, as well as a first evaluation of the measurements performed during beam irradiation. The analysis of the collected data suggests that a representative reproduction of the operational conditions of the beam dump facility target was achieved during the prototype tests, which will be complemented by a postirradiation examination campaign during 2020

SPS Beam Dump Facility - Comprehensive Design Study

The proposed Beam Dump Facility (BDF) is foreseen to be located in the North Area of the Super Proton Synchrotron (SPS). It is designed to be able to serve both beam-dump-like and fixed-target experiments. The SPS and the new facility would offer unique possibilities to enter a new era of exploration at the intensity frontier. Possible options include searches for very weakly interacting particles predicted by Hidden Sector models, and flavour physics measurements. Following the first evaluation of the BDF in 2014–2016, CERN management launched a Comprehensive Design Study over three years for the BDF. The BDF study team has executed an in-depth feasibility study of proton delivery to target, the target complex, and the underground experimental area, including prototyping of key subsystems and evaluations of radiological aspects and safety. A first iteration of detailed integration and civil engineering studies has been performed to produce a realistic schedule and cost. This document gives a detailed overview of the proposed facility together with the results of the in-depth studies, and draws up a road map and project plan for a three years Technical Design Report phase and a five–six years construction phase.The proposed Beam Dump Facility (BDF) is foreseen to be located in the North Area of the Super Proton Synchrotron (SPS). It is designed to be able to serve both beam-dump-like and fixed-target experiments. The SPS and the new facility would offer unique possibilities to enter a new era of exploration at the intensity frontier. Possible options include searches for very weakly interacting particles predicted by Hidden Sector models, and flavour physics measurements. Following the first evaluation of the BDF in 2014–2016, CERN management launched a Comprehensive Design Study over three years for the BDF. The BDF study team has executed an in-depth feasibility study of proton delivery to target, the target complex, and the underground experimental area, including prototyping of key subsystems and evaluations of radiological aspects and safety. A first iteration of detailed integration and civil engineering studies has been performed to produce a realistic schedule and cost. This document gives a detailed overview of the proposed facility together with the results of the in-depth studies, and draws up a road map and project plan for a three years Technical Design Report phase and a five–six years construction phase