STFC/RAL, Chilton, Didcot, Oxon
Exeter University, Exeter, Devon
Gericke LTD, Ashton-under-Lyne
This paper describes the potential of fluidised powdered material for use as a particle production target in high power particle accelerator based facilities. In such facilities a multi-MW proton beam is required to interact with a dense target material in order to produce sub-atomic particles, e.g. neutrons for a neutron source or pions for a so-called conventional neutrino beam, a neutrino factory or a muon collider. Experience indicates that thermal transport, shock wave and radiation damage will limit the efficiency and reliability of facilities utilising solid targets at around 1 MW beam power. Consequently liquid mercury has been adopted as the target technology for the latest neutron facilities SNS and J-SNS at ORNL and Tokai respectively, and is the baseline for a neutrino factory and muon collider. However mercury introduces new problems such as Cavitation Damage Erosion. This paper discusses how a fluidised powder target may combine many of the advantages of a liquid metal with those of a solid, and describes an experimental programme at RAL currently underway to implement this technology.
BNL, Upton, Long Island, New York
STFC/RAL/ASTeC, Chilton, Didcot, Oxon
STFC/RAL, Chilton, Didcot, Oxon
ORNL, Oak Ridge, Tennessee
CERN, Geneva
PU, Princeton, New Jersey
Fermilab, Batavia
We report on the analysis of data collected from the optical diagnostics of the MERIT experiment which was run at CERN in the fall of 2007. The breakup of the free mercury jet resulting from the impact of intense proton beams from the CERN PS within a magnetic field environment is described.
STFC/RAL, Chilton, Didcot, Oxon
Exeter University, Exeter, Devon
Gericke LTD, Ashton-under-Lyne
This paper proposes a technology based on fluidized powder which could be employed as a high power target (and beam dump), for example in a future Neutrino Factory or Muon Collider. A fluidized powder target is believed to bring together some advantages of both the solid and liquid phase whilst avoiding some of their drawbacks. The current Neutrino Factory and Muon Collider proposals require the use of a high Z target material withstanding beam ionisation heating of around 1 MW. The article proposes to use a dense tungsten powder jet as an alternative to the baseline open mercury jet for interaction with the proton beam inside the high field capture solenoid. The preliminary experimental results on the production and on the characteristics of a dense horizontal tungsten powder jet are presented. The morphology of the jet is analysed and presented as a function of the driving parameters (e.g. pneumatic supply pressure, boundary conditions of the jet, etc.). A test rig was developed to investigate the reliability of lean and dense phase pneumatic conveying of tungsten powder and the results of such experiments are discussed in the paper.
Sheffield University, Sheffield
University of Warwick, Coventry
STFC/RAL/ISIS, Chilton, Didcot, Oxon
STFC/RAL/ASTeC, Chilton, Didcot, Oxon
STFC/RAL, Chilton, Didcot, Oxon
Funding: Science and Technology Facilities Council (United Kingdom)
The UK programme of high power target developments for a Neutrino Factory is centred on the study of high-Z materials (tungsten, tantalum). A description of lifetime shock tests on candidate materials is given as a part of the research into a solid target solution. A fast high current pulse is applied to a thin wire of the sample material and the lifetime measured from the number of pulses before failure. These measurements are made at temperatures up to ~2000 K. The stress on the wire is calculated using the LS-DYNA code and compared to the stress expected in the real Neutrino Factory target. It has been found that tantalum is too weak at these temperatures but a tungsten wire has reached over 26 million pulses (equivalent to more than ten years of operation at the Neutrino Factory). Measurements of the surface velocity of the wire using a laser interferometry system (VISAR) are in progress, which, combined with LS-DYNA modelling, will allow the evaluation of the constitutive equations of the material. An account is given of the optimisation of secondary pion production and capture in a Neutrino Factory and of the latest solid target engineering ideas.
PU, Princeton, New Jersey
STFC/RAL/ASTeC, Chilton, Didcot, Oxon
STFC/RAL, Chilton, Didcot, Oxon
ORNL, Oak Ridge, Tennessee
CERN, Geneva
BNL, Upton, Long Island, New York
Fermilab, Batavia
The MERIT (MERcury Intense Target) experiment was run in the fall of 2007 using 14 and 24 GeV intense proton beams from the CERN PS. It is a proof-of-principle experiment designed to validate a target concept for producing an intense muon source for a future muon collider or neutrino factory. The experiment successfully demonstrated a target technique for multi-MW proton beams that utilizes a free-flowing liquid metal jet within the confines of a high-field solenoid. We describe the experimental strategy and parameters, as well as the results obtained and their implications for future muon-based accelerator facilities.
CERN, Geneva
STFC/RAL/ASTeC, Chilton, Didcot, Oxon
STFC/RAL, Chilton, Didcot, Oxon
ORNL, Oak Ridge, Tennessee
BNL, Upton, Long Island, New York
PU, Princeton, New Jersey
Fermilab, Batavia
The MERIT experiment is a proof-of-principle test of a target system for high power proton beam to be used as front-end for a neutrino factory complex or a muon collider. The experiment took data in autumn 2007 with the fast extracted beam from the CERN Proton Synchrotron (PS) to a maximum intensity of about 30·1012 protons per pulse. We report results from the portion of the MERIT experiment in which separated beam pulses were delivered to a free mercury jet target with time intervals between pulses varying from 2 to 700 microseconds. The analysis is based on the responses of particle detectors placed along side and downstream of the target.