The Physics Program at MAMI-C

a r X i v :0802.2870v 2 [n u c l -e x ] 7 A p r 2008The Physics Program at MAMI-C

the Structure of the Nucleon

September 10-14, 2007

IKP , Forschungzentrum Jülich, Germany

Patrick Achenbach Institut f¨u r Kernphysik Johannes Gutenberg-Universit¨a t J.-J.-Becher-Weg 45D-55099Mainz,Germany Email:patrick@kph.uni-mainz.de Abstract In February 2007,the fourth stage of the Mainz Microtron,MAMI-C,started operations with a ?rst experiment.The new Harmonic Double-Sided Mi-crotron delivers an electron beam with energies up to 1.5GeV while pre-serving the excellent beam quality of the previous stages.The experimental program at MAMI is focused on studies of the hadron structure in the do-main of non-perturbative QCD.In this paper,a few prominent selections of the extensive physics program at MAMI-C will be presented.1The new 1.5GeV Harmonic Double-Sided Microtron as the Fourth Stage of MAMI The Mainz Microtron MAMI is a unique facility in Europe to study the hadron structure with the electromagnetic probe at small momentum trans-fers [1].MAMI comprises a cascade of three race-track microtrons (RTM),delivering since 1991a high-quality 855MeV,100μA cw-electron beam [2],which was energy upgraded by a fourth stage,MAMI-C,in recent years [3].

Realizing the fourth stage as another RTM was evidently impossible:the two 180?-bending magnets would have had a weight of approx.2×2000tons for an end-point energy of 1.5GeV.However,for the next higher polytron con?guration,the Double-Sided Microtron (DSM),this weight is reduced by a factor of four.By operating at 4.90GHz,the ?rst harmonic of the fun-damental 2.45GHz radio-frequency (rf),the necessary coherent energy gain per turn for the two normal conducting linacs is reduced to get a moderate power consumption.For achieving a simple transverse optics the strong ver-tical fringe ?eld defocusing of the four 90?-bending magnets is compensated

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Patrick Achenbach The Physics Program at MAMI-C

Patrick Achenbach The Physics Program at MAMI-C

Patrick Achenbach The Physics Program at MAMI-C

Patrick Achenbach The Physics Program at MAMI-C

Patrick Achenbach The Physics Program at MAMI-C

Patrick Achenbach The Physics Program at MAMI-C

Patrick Achenbach The Physics Program at MAMI-C

Patrick Achenbach The Physics Program at MAMI-C

Patrick Achenbach The Physics Program at MAMI-C