Experimental proposal to study emittance growth in the existing ATF EXTSeryi, M. Woodley, and F. ZhouSLAC08/30/07

OutlineMotivation: to look for emittance growth source, and check how well the coupling correctionGeneration of local bumps in the EXT and to see the effects.Close the ring orbit Hardware requirements: an additional vertical corrector only.08/30/07

EXT local bump generationQ6, Q7, and septum1-308/30/07

More closeZV9R ZH9RZV1XZX1XV1 add by us H1- add by Naito08/30/07

Either x or y offset: vertical normalized emittance growth(W/o any correction)Y=0 (nominal) X=0 (nominal)X (mm)Y (mm)y (nm)y (nm)Either x or y offset in the existing EXT channelIncludes QM7+Septum1 multipoles 08/30/07

Combined x and y offset: vertical emittance growth Combined x and y offset in the EXT channelQM7+Sep1 multipoles. x w/o correction x w/ correctiony (nm)y (nm)Y=1 mmX=5 mmX (mm)Y (mm)08/30/074030

Vertical phase spaces at EXT end

x/y=0/0, no multi x/y=-5/1mm, w/o correction x/y= 5/1mm, w/o correction x/y=0/0,no multi x/y=5/0mm, w/o correction x/y=0/1mm, w/o correction x/y=0/0,no multi x/y=5/1mm, w/o correction x/y=5/1mm, w/ correctiony y y y 08/30/07

Close the ring orbit At EXT line: X=5mm y =1.5mmZV9R ZH9RZH10R ZV10RZH11R ZV11R08/30/07wiggler off4-6mm

Beam experiment Observe the effects vs different bump amplitude; it can help us to understand the emittance growth source, and also how well the coupling correction: Only x or y bumpsW/o correctionW/ correctionCombined x+y bumpsW/o correctionW/ correctionTotal 6 correctors needed to generate local bumps; 4 correctors (2 H and 2 V) already exist, another H corrector probably already exists.08/30/07

H corrector, install by Summer 2007? Naito ATF TN, May 2007V corrector, need to install for this test08/30/07

Stripline kicker test layoutcan we rotate it for V corrector? for H corrector

RequirementsOnly 1 vertical correctors need to be installed or just rotate a H corrector assume strip-line kicker experiment install all other horizontal correctors by summer 2007.Corrector parameters:Horizontal 5 mm offset (ok if stripline kicker experiment ready)1.5mrad (max); B*L=6E-3 T.m; B~0.14 T assume L=5cmVertical offset 1.5 mm offset 0.3 mrad (max)B*L=1.3E-3 T.m; B

SummaryInitial y is 30 nm. Final emittance and phase spaces are measured at the existing EXT end. No magnet errors employed except the QM7 and Septum1 multipoles. Tracking results:At the nominal position: only x-offset does not create vertical emittance growth while only y-offset create vertical emittance growth w/o corrections. Combined both x and y offsets create severe vertical emittance growth w/o corrections; combined offsets x/y=5/1mm and 5/1.5mm can create 30% and 50% vertical emittance growth after all corrections. The beam test will be helpful to understand the emittance growth source and also how well the coupling correction.What we require:need 1 more vertical corrector or even just rotate 1 H corrector for V corrector assume the stripline experiment is ready; Beam time: probably two runs (test run and 2nd run for data taking)??08/30/07