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LEPS Collab. Meeting Academia Sinica, Jan. 13, 2006. Possible further extensions in the new LEPS beamline in Spring-8. S. Daté Accelerator Division, SPring-8/JASRI. Contents. Introduction A short summary of previous discussions on energy upgrade above 5 GeV
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LEPS Collab. Meeting Academia Sinica, Jan. 13, 2006 Possible further extensions in thenew LEPS beamline in Spring-8 S. Daté Accelerator Division, SPring-8/JASRI
Contents Introduction A short summary of previous discussions on energy upgrade above 5 GeV A new estimate of high energy gamma yield for X-ray re-injection scheme Conclusion
1. Introduction LEPS experiments have proved the accessibility to new frontiers in hadron physics by making use of its advantages in measuring the forward angular regions without harmful background noise and manipulating gamma ray characteristics through easy-to-access laser system. They also enjoy highly stable operation of Spring-8 accelerators and its low emittance electron beams. After 5 years of physics runs with several important outputs, we are in a position to discuss a new LEPS beamline with enhancement and emphasis of recognized advantages, supplements to weak points, and challenges to completely new possibilities, which all motivated by physics.
Directions of extentions • Energy • -> 3.5 GeV in near future (Laser upgrade) • ~> 4 - 6 GeV ? • Intensity -> 107-8/s (high power laser, LRNB, high current, round beam, new tagging system) • Detector • Polarized target
HLEP generation by X-ray re-injection (2) Diamond mirror 8 GeV 100 mA SR Undulator X-ray mirror Eg < 7.4 GeV Reflectivity = 0.810 = 10% Ex =100 eV
A short summary of previous discussions Gamma yield = X-ray generation V reflection & re-injection V gamma ray production
˙ d I / I e dE g Cross section depends on photon energy ,
Can s be mm2 ? Re-focussing Thin undulator approximation 275x2 mm ~100 mrad e- 6x2 mm spherical mirror In principle, yes.
Bunch mode dominance 60 cm 100 mrad . . . e- h ~ 275 mm v ~ 6 mm
Bunch-bunch collisions Limit: Heat load at finger contact ~ 174 bunch filling Maximum:
Conclusion • Provided • an undulator with • high reflectable (R > 0.1)spherical mirror for 100 eV photons • with timing adjustment system (mirror position z = 24 +- 2 m, dz = 6mm) We may obtain in principle.
The maximum yield of gamma in 5~6 GeV region attainable in Spring-8 SR: => in an 1A, 1.5 GeV SR: => Conclusion in the meeting on Oct. 20, 2005
, ˙ I d / R / I e dE g Cross section convoluted with Nph †
kG An undulator to produce 100 eV photons Matching of the first harmonics: K > 2
˙ N d ph / I e d w † Yield of X-ray photons ( )
Physics @workshop • Exotics: • Q+, L(1405), S11(1535) ---- 5q • X(Kp-bound), C(1480)fp ---- 4q • glueball, hybrid, odderon(odd-glueball) --- multi-g(+qq) • Dirac monopole • High precision: • hyperon photoproduction • nucleon resonance (e.g. gpol +p p0 + p_pol ) • A-dependence – mean free path • nonmesonic decay of hypernucleus • Compton scattering – nucleon swelling • p0,h –lifetime, polarizability, s Primakoff (high Eg, forward) • Others: • J/y from d or A (c.f. Eth(g+p J/y +p)=8.1 GeV) CP violation (hpp) GDH • polarized HD target