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TY - CONF AU - Sutter, D.F. AU - Beaudoin, B.L. AU - Dovlatyan, L. ED - Yamazaki, Yoshishige ED - Raubenheimer, Tor ED - McCausey, Amy ED - Schaa, Volker RW TI - Off Axis Dependence of Current Dependent Coherent Tune Shifts in the UMER Ring J2 - Proc. of NAPAC2019, Lansing, MI, USA, 01-06 September 2019 CY - Lansing, MI, USA T2 - North American Particle Accelerator Conference T3 - 4 LA - english AB - The University of Maryland Electron Ring (UMER) was built to explore space charge effects in the extreme - beyond the space charge limit of most existing storage rings. At the nominal operating kinetic energy of 10 keV, the beam is also non relativistic. We have experimentally verified that the current dependent coherent tune shift obeys the Laslett formula over a wide current range for a cylindrical geometry and non penetrating magnetic fields when the beam is on axis; i.e. the average closed orbit displacement around the ring is essentially zero.* In the current experiment this measurement is extended to the change in current dependent coherent tune shift as the average closed orbit is moved off axis. It can be displaced over approximately ±10 mm of the vacuum pipe diameter of 50 mm without loss of beam. Because the 36 bending magnets in UMER are very short, we treat each of them as a local kick and then increment each by a calculated small amount to achieve the desired, global closed orbit displacement. Experimental results are compared to predictions by Zotter and others. PB - JACoW Publishing CP - Geneva, Switzerland SP - 422 EP - 425 KW - experiment KW - space-charge KW - electron KW - dipole KW - storage-ring DA - 2019/10 PY - 2019 SN - 2673-7000 SN - 978-3-95450-223-3 DO - doi:10.18429/JACoW-NAPAC2019-TUPLM22 UR - http://jacow.org/napac2019/papers/tuplm22.pdf ER -