Magnet Test Bill Bugg Steve Berridge

1. Magnet TestBill Bugg Steve Berridge Proposal

2. Purpose is to test understanding of magnetic spectrometer with Beta source Measure endpoint and shape of the known Sr-90 beta spectrum. This looks at lens spectrometer system at relatively low currents. Measure with different jaw openings (jaws scans) Do a series of low current lens-spectrometer scans Measure the field variation with spectrometer current at several points inside the dipoles with a Hall probe. . The first 3 provide a hopefully stringent test of the lens spectrometer simulation and the last provides information( I think) on field dependence of mu.

3. We will perform a very simple measurement using silicon detectors At the exit window of the spectrometer will place the Possi counter to count the electron flux exiting the spectrometer as in the experiment and to serve as trigger for the ADC gate. At an adjustable distance from the window will be a a 7 segment silicon detector to measure the position spectrum of the electrons at either the exit window or the reconversion target. Counts are recorded on 11 scalars and pulse heights on Lecroy ADC;s. We use spectroscopy amplifiers to process the silicon signals so that single electrons can be detected. The detectors have been tested by Steve at Tennessee with a beta souce and Zen will provide a labview DAQ program. We will begin around December 1 for setup and take data for about 1 week.

4. Just a brief word on endpoint determination. Fermi theory of Beta decay predicts a spectrum shape such that Sqrt[N(p)F]/p is a straight line when plotted against T and goes to 0 at the endpoint energy One can also rewrite this as Sqrt[N(T)/FEp] which also goes to 0 at endpoint These plots are called Kurie plots and are the standard way beta endpoints are measured by beta spectrometers. Our transport system is a beta spectrometer(althought not a really good one for this purpose. Karim has simulated the performance of out system with mu=4.