Experimental proposal to study emittance growth in the existing ATF EXTSeryi, M. Woodley, and F. ZhouSLAC09/05/07 Thank J. Amann, S. Seletskiy, C. Spencer for magnetic modeling and field fitting.

OutlineMotivation: to look for emittance growth source, and check how well the coupling correctionField map of the QM7 and BS1X Generation of local bumps in the EXT and observed effects.Close the ring orbit Hardware requirements: an additional vertical corrector only.09/05/07

Field map of QM7 and BS1XNominal positionQM7BS1XBS1XByBxBy, BxX (m)ByBx

EXT local bump generation09/05/07QM6QM7QM5BS1XBS2XBS3Xkicker1ZV1XQD1XBH1x(ZX1x)

More close09/05/07kicker1zv9zH9QM5QM6QM7BS1XBS2XBS3XZV1X1 H corrector, which maybe ready by Naitos group1 V corrector, which needs to be installedQD1XBH1x(ZX1x)

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+BS1X multipoles 09/05/07

Combined x and y offset: vertical emittance growth Combined x and y offset in the EXT channelQM7+BS1X multipoles. x w/o correction x w/ correctiony (nm)y (nm)Y=1 mmX=5 mmX (mm)Y (mm)09/05/074030

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 09/05/07

Close the ring orbit Bump generated at QM7 at EXT: X=5mm y =1.5mm09/05/07wiggler off4-6mmzv9zH9QM5kicker1QM6QM7QM8QM9kIIQM10zH10zV10QM11ZH11QM12ZV11H corrector (probably already ready by Naitos group)V corrector, which needs to be installed

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.09/05/07

H corrector, installed by Naito group by Summer 2007? V corrector, which needs to be installed 09/05/07

Stripline kicker test layoutSuggest to install V corrector for this test H corrector, installed by Naito group?09/05/07

RequirementsSuggest to install 1 vertical corrector only assume strip-line kicker experiment installed all other horizontal correctors by summer 2007.Corrector parameters:Horizontal 5 mm offset 1.5mrad (max); B*L=6E-3 T.m; B~0.14 T assume L=5cm (probably is ready by the Naito experiment)Vertical 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:Suggest to install 1 more vertical corrector assume the stripline experiment installed other H correctors. Beam time: initially, probably two shifts (test shift for bump generation and calibration, and 2nd shift for data taking). 09/05/07