Perspectives for an energy increase of MAMI C Andreas Jankowiak Institut für Kernphysik Johannes Gutenberg – Universität Mainz Cristal MAMI Collaboration Meeting

Andreas Jankowiak, Institut für Kernphysik, Johannes Gutenberg – Universität Mainz Present situation 855.3MeV, E =0.013MeV (0.001%) (883.1MeV maximum) max. 103 A cw current h =8 nm rad, v =0.5 nm rad (allows for beam foci of ~ m) Halo: 5 r MAMI B

Andreas Jankowiak, Institut für Kernphysik, Johannes Gutenberg – Universität Mainz Present situation MeV, E =0.100MeV (0.007%) max. 100 A cw current (successful tested) h =12 nm rad, v =2 nm rad (measured, v definitely overestimated) MAMI C

Andreas Jankowiak, Institut für Kernphysik, Johannes Gutenberg – Universität Mainz What defines the end energy of an RTM: 1 i i+1 E d magnet distance E Inj ( 1) 2R E out =E Inj +z E dynamic coherence-condition: static coherence-condition : k,n: integer numbers

Andreas Jankowiak, Institut für Kernphysik, Johannes Gutenberg – Universität Mainz increase B and adjust E to full fill dynamic condition adjust E inj to full fill static condition Increasing the end energy of an RTM: Energy increase by factor means:

Andreas Jankowiak, Institut für Kernphysik, Johannes Gutenberg – Universität Mainz What defines the end energy of a DSM dynamic coherence-condition: static coherence-condition : E inj k,n=1: integer numbers Energy increase by factor means (as for RTM):

Andreas Jankowiak, Institut für Kernphysik, Johannes Gutenberg – Universität Mainz What defines the end energy of a HDSM In reality our machine (Harmonic Double Sided Microtron) is a little bit more complicated but the scaling is the same ! Energy increase by factor means (as for RTM): Energy gain per turn total linac II (2.45GHz) linac I (4.90GHz) beam energy E inj =855.11MeV E out =(1508.4±0.4) MeV B max =1.539T

Andreas Jankowiak, Institut für Kernphysik, Johannes Gutenberg – Universität Mainz E out =1508.4MeV E out = MeV E in E in =855.12MeV E out =180.03MeV E in E out =14.86MeV E in =3.97MeV Energy of the HDSM Therefore: Changing the maximum energy by factor implies scaling of all machines by factor (E and B fields) The maximum energy of RTM3 used so far is: 883.1MeV ! Scaling the HDSM by 883.1/855.3 (+3.25%) results in MeV beam energy of the HDSM.

Andreas Jankowiak, Institut für Kernphysik, Johannes Gutenberg – Universität Mainz Increasing the magnetic field of the HDSM dipoles defocusing focussing remember: dipoles incorporates field gradient perpendicular to the pole face to compensate vertical defocusing necessary field accuracy: B/B ~ (bending angle errors, longitudinal beam dynamics)

Andreas Jankowiak, Institut für Kernphysik, Johannes Gutenberg – Universität Mainz Increasing the magnetic field of the HDSM dipoles HDSM dipole 03, field map (normalized to ideal field gradient, B max =1.539T for 1508MeV) without correction with correction

Andreas Jankowiak, Institut für Kernphysik, Johannes Gutenberg – Universität Mainz Increasing the magnetic field of the HDSM dipoles HDSM DIPOLE 02 at higher fields, more details 1.53T, without correction 1.53T with correction 1508MeV

Andreas Jankowiak, Institut für Kernphysik, Johannes Gutenberg – Universität Mainz Wedler Shim s LINAC-Side Wedler Shim s Dispersions-Side Increasing the magnetic field of the HDSM dipoles Missing field: Correction with thin iron shim (designed for fields at 1.539T) and corrector magnet ! (angle error ~ mrad)

Andreas Jankowiak, Institut für Kernphysik, Johannes Gutenberg – Universität Mainz T Increasing the magnetic field of the HDSM dipoles We measured field maps for all magnets at nominal field 1.539T = 1.508GeV (of course) 1.635T = 1.602GeV 1.708T = 1.674GeV 1.635T, without correction 1.635T with correction 1602MeV

Andreas Jankowiak, Institut für Kernphysik, Johannes Gutenberg – Universität Mainz surface correction plates shims corrector magnets Increasing the magnetic field of the HDSM dipoles corrector magnets system

Andreas Jankowiak, Institut für Kernphysik, Johannes Gutenberg – Universität Mainz Increasing the magnetic field of the HDSM dipoles corrector magnets system (design max values: horizontal 3mrad, vertical 1.5GeV)

Andreas Jankowiak, Institut für Kernphysik, Johannes Gutenberg – Universität Mainz What does that mean ? First step (ca. 11/2008) (new colleague in our group, Robert Heine, will start and will be in charge to study the possibilities of an energy increase) Inject 883.1MeV beam, increase HDSM magnetic field by 3.25% to 1.589T and klystron output power by 6.6% HDSM = MeV Could (should) work ! Will learn much about the behaviour of the dipoles! (excitation pattern of corrector magnets) This test is the basis for all further attempts ! drawback: e.g. strengths of power supply in transfer channel (to A1) is very near to the limit. Next steps: Depending on these results and their careful analysis !

Andreas Jankowiak, Institut für Kernphysik, Johannes Gutenberg – Universität Mainz What does that mean ? Any further increase needs: higher extraction energy from RTM3 and therefore complete scaling of linac and all RTMs. E.g. RTM3 dipole PS (609A, 310V) is at (96%)! limit for RTM3 Energy ~900MeV MeV max. We are currently checking all components concerning their capabilities. First look: 4 magnets ~ injector linac klystron 4.90GHz klystron and 100 A and 50 A proper adjustment (in advance by field measurements and magnet cycling) of the relation of reverse field and main field of all RTM dipoles (not possible just to scale, especially critical at RTM2) no simple knob for increasing E inj available At certain energies it will require new hardware !

Andreas Jankowiak, Institut für Kernphysik, Johannes Gutenberg – Universität Mainz What does that mean ? new power supply for RTM3 dipoles, new injector linac klystron + PS (what else ?) new surface correction plates and shims (needs to be designed based on already existing field maps up to 1.708T = 1.674GeV, not clear if possible because current line density in corners will dramatically increase) their installation would need to dismantle most of the HDSM hardware (4.90GHz linac, return path vacuum system, radiation shielding ) For high beam current operation: new 4.90GHz klystrons with higher output power E max = 1600MeV need E Inj =907MeV (13% increase in rf-Power) E max = 1650MeV need E Inj =936MeV (20% increase in rf-power)

Andreas Jankowiak, Institut für Kernphysik, Johannes Gutenberg – Universität Mainz Conclusion: 1557MeV HDSM should be possible (will be tested till end of 2008) further exploration depending on results of test - not simple and will most likely need new hardware - at certain energy (my estimation between 1.560GeV and 1.6GeV) new correction plates (very elaborate) necessary - at certain energy klystrons will be at their limit superconducting post accelerator some basics real estate gradient (cw): ~ 10 MV/m 100MeV needs 10m cost: more expensive than HDSM (> 15Mio) no space where all experimental halls can benefit from increase