Preliminary Measurements of Spontaneous Radiation Output from the UK Free Electron Laser

The electromagnetic radiation generated by ultra-relativistic positrons channeling in a crystalline undulator is discussed. The crystalline undulator is a crystal whose planes are bent periodically with the amplitude much larger than the interplanar spacing. Various conditions and criteria to be fulfilled for the crystalline undulator operation are established. Different methods of crystal bending are described. We present the results of numeric calculations of spectral distributions of the spontaneous radiation emitted in the crystalline undulator and discuss the possibility to create the stimulated emission in such a system in analogy with the free electron laser. A careful literature survey covering the formulation of all essential ideas in this field is given. Our investigation shows that the proposed mechanism provides an efficient source for high energy photons, which is worth studying experimentally.

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THE UK FREE ELECTRON LASER

Le Journal de Physique Colloques ◽

10.1051/jphyscol:1983117 ◽

1983 ◽

Vol 44 (C1) ◽

pp. C1-179-C1-183 ◽

Cited By ~ 1

Author(s):

M. W. Poole ◽

S. D. Smith

Keyword(s):

Free Electron ◽

Free Electron Laser ◽

The Uk

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A Free Electron Laser–Photoemission Electron Microscope System (FEL–PEEM)

Surface Review and Letters ◽

10.1142/s0218625x98001596 ◽

1998 ◽

Vol 05 (06) ◽

pp. 1257-1268 ◽

Cited By ~ 53

Author(s):

H. Ade ◽

W. Yang ◽

S. L. English ◽

J. Hartman ◽

R. F. Davis ◽

...

Keyword(s):

Electron Microscope ◽

Energy Range ◽

Photon Energy ◽

Free Electron ◽

Free Electron Laser ◽

Spontaneous Radiation ◽

Laser Photoemission ◽

Emission Mode ◽

First Results ◽

Photoemission Electron

We report first results from our effort to couple a high resolution photoemission electron microscope (PEEM) to the OK-4 ultraviolet free electron laser at Duke University (OK-4/Duke UV FEL). The OK-4/Duke UV FEL is a high intensity source of tunable monochromatic photons in the 3–10 eV energy range. This tunability is unique and allows us to operate near the photoemission threshold of any samples and thus maximize sample contrast while keeping chromatic berrations in the PEEM minimal. We have recorded first images from a variety of samples using spontaneous radiation from the OK-4/ Duke UV FEL in the photon energy range of 4.0–6.5 eV. Due to different photothreshold emission from different sample areas, emission from these areas could be turned on (or off) selectively. We have also observed relative intensity reversal with changes in photon energy which are interpreted as density-of-state contrast. Usable image quality has been achieved, even though the output power of the FEL in spontaneous emission mode was several orders of magnitude lower than the anticipated full laser power. The PEEM has achieved a spatial resolution of 12 nm.

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