Review of new High Energy Rings Sergey Sinyatkin SuperB Frascati Meeting September 28, 2010

Goals of the new rings - Decrease chromaticity of the ring. - Optimization of chromaticity correction sections in an experimental region. - Decrease overall dimensions of the ring.

Changes of HER lattice The following changes of HER lattice taken from Pantaleo are made: - Geometry is closed. - 66 mrad angle is introduced between the LER and HER at IP. - Optics is re-matched. - Corrections of chromaticity functions are made.

Twiss functions of arc cell HER old 12 version To reduce chromaticity three lenses and two magnets are replaced by five weaker lenses and six magnets. Bending radius of the new 4 magnets is 117 m. Length is 2 meters. Bending radius of the 2 magnets is 80 m. Length is 2 meters. The quadrupoles strengths are reduced by 17 %. Chromaticity of a cell decreased 13 %. HER modified 12 version

Twiss functions of arc cell HER modified 12 version To reduce circumference of the ring angle of the cell is increased from 0.387 rad to 0.58 rad. New additional bending magnets and quadrupoles are introduced to obtain large angle of the new cell. Bending radius of dipoles is 76 m. Length is 1.4 m and 4.7 m for short and long magnets respectfully. HER new short version

Parameters of HER regular cell Length of a cell of new compact structure is more than for 12 versions. Parameters of cell V12 old V12 mod New short lat. L, m 59.89 60.49 76.07 Num. cell 12 8 Angle, rad 0.387 0.580 Qx 2.2821 2.2770 3.8000 Qy 0.7532 0.7693 1.2730 Cx0 (sext. Off) -4.81 -4.17 -4.89 Cy0 (sext. Off) -2.68 -2.34 -3.66 I2, m-1 4.6327E-03 4.5431E-03 7.6497E-03 I5, m-1 1.2457E-07 1.3043E-07 1.9389E-07 Number of cells in the short version is less than one in 12 versions. For comparison with the old 12 version a reduction of total horizontal chromaticity of arcs is 13% and 32 % for modified and short lattices. V12 old V12 mod. New short lat.

Scheme of sextupole compensation V12 Old Green lines show sextupoles in the cell. V12 mod -I is minus unitary map between sextupoles. New Short ring

Twiss functions of experimental region HER old version Main sextupoles of chromaticity correction section of QD0 lens. Main sextupoles of chromaticity correction section of QF1 lens. Dispersion function is increased to make additional sextupoles more effective. Additional sextupoles to correct nonlinear chromaticity. New 3 dipoles, to increase dispersion. HER new version

Synchrotron radiation integrals of experimental region New additional dipoles decrease synchrotron radiation.

Twiss functions of V12 modified and short rings New Short ring

Parameters of the rings Circumference of short ring is less by 100 m than the 12 versions. Parameters of the cell V12 old V12 mod New short lat. L, m 1258.4 1263.5 1159.5 Qx 40.575 43.575 Qy 17.595 18.595 19.595 Cx0 (sext. Off) -134.7 -125.1 -112.8 Cy0 (sext. Off) -449.3 -448.5 -443.2 I2, m-1 7.4360E-02 7.3489E-02 7.8903E-02 I5, m-1 2.2350E-06 2.3308E-06 2.3161E-06 Em, nm*rad 2.0 2.1 1.9 Betatron tunes of short version are higher but chromaticity is smaller than in 12 version. Emittances of the rings are the same.

Chromatic functions of V12 mod and short rings The chromaticity of betatron functions is well suppressed by sextupoles of chromaticity correction sections. New Short ring

IP beta functions The band width for modified 12 and short rings is 1.8 % and 1.4 %. Energy acceptance is more than 2 %. V12 mod Band width ~ 1.8 % New Short ring Band width ~ 1.4 %

Layout of HER lattices (V12 mod & new short) Circumference: V12mod = 1263.5 m New short = 1159.5 m The short lattice is required for possible new placement of the ring. Width of the short ring is smaller by 23 m. Height of the short ring is smaller by 48 m.

Conclusion The geometry of new HER lattices is closed. The new lattices provide main parameters. The short version of the ring is available.