MICE TARGET OPERATION C. Booth, P. Hodgson, R. Nicholson, P. J. Smith, Dept. of Physics & Astronomy University of Sheffield, England. for PAC09 1 – The MICE Experiment2 - The Target Mechanism 4 –Target Monitoring & Signals 5 –Target Stability 6 –Beam-loss as a Function of Target Actuation Depth 7 – Correlation to MICE muon rate The aim of MICE is to construct a section of cooling channel that is long enough to demonstrate a measurable cooling effect by reducing the transverse emittance of a muon beam by the order of 10%. The MICE detectors and instrumentation will be able to achieve an absolute accuracy on the measurement of the emittance to 0.1% or better. Fast emittance reduction will be an important step towards a future neutrino factory. The MICE target has been designed to operate parasitically on the ISIS accelerator at the Rutherford Appleton Laboratory, by inserting a small titanium paddle into the proton beam during the last couple of ms before beam extraction. Further details of the MICE target hardware can be found on a separate poster. The first operational target was installed on ISIS in January 2008 and remained operational for a period of approximately one year. The diagram above illustrates the signals that are recorded by the target DAQ when the target is operating. Target trajectory Fit to target trajectory ISIS beam intensity ISIS total beam-loss Fit to total beam-loss caused by the MICE target mechanism The MICE target needs to intercept only the last couple of ms of the ISIS spill, catching the protons when they are at their highest energy. The beam-loss signal is created by the summation of the signals received from a series of gas ionisation chambers situated around ISIS. The beam- loss signal is representative of the rate of proton loss from the synchrotron. For a given rate the strength of the beam-loss signal is dependent upon the proton energy. The ability of the target to reproducibly attain a given actuation depth is shown in the graphs below. The deviation is much less than that of the proton beam which can vary by up to a couple of mm. Only short continuous runs of a few thousand pulses at a particular actuation depth have been possible on ISIS so far; longer test runs using an identical actuator in the laboratory have shown similar results for millions of actuations. 3 –Target Operation in 2008 During 2008 the target was run for approximately 185,000 actuations. The operational run time for the target was limited, so the majority of this time was used to commission the MICE beam-line and to further understand the interaction of the MICE target with the ISIS beam. The actuation depth and exact insertion time of the target were set so that the amount of beam-loss produced by the target could be controlled to within the limits set by the normal variation in the position of the ISIS beam from pulse to pulse. The amount of beam-loss produced by the MICE target has been limited whilst its activation effect on the local environment is studied and understood. However, even with the limited data obtained so far it has been possible to establish the relationship between the target’s actuation depth and the produced beam-loss and to demonstrate that the beam-loss produced by the target can be well controlled. The current levels of beam-loss are consistent with a rate of a few muons per spill into the MICE cooling channel. As MICE needs several hundred muons per spill the permitted beam-loss caused by the target will need to be increased significantly to obtain the required muon rate for MICE. Each data point represents the mean value over 6 minutes of data (144 points). AND MONITORING