E-206 Compressed beam studies
Shift One
Goal: Measure the THz emitted from a smaller and more circular electron spot on the foil than FY12
Motivation: A large spot should decrease the THz output at higher frequencies to the extent that
emission of these wavelengths from different parts of the foil interfere destructively. We want to find
out how small we have to make the spot to reach the maximum emission for various bunch lengths.
So we need to do the following for three sets of optics (the typical optics for this run, optics with the
smallest THz size consistent with a small beam at the IP, and optics that focus at the THz foil):
Shift One
Beam Configuration: Nominal for 30x30 at the MIP. Beam charge (1 nC), Bunch length (30um), Rep
rate 10Hz. Minimal dispersion. Most important parameter is the good compression.
Procedure:
1.
Measure the beam size on the foil with OTR.
2.
Measure the THz energy emitted and the spectrum (with the interferometer).
3.
Measure the focal spot with the knife edge.
Time estimate: 1 hour
Shift Two
Beam Configuration: Transverse beam size at USTHz foil needs to be <100 um in x and y. Beam
charge (1 nC), Bunch length (30um), Rep rate 10Hz. Minimal dispersion. Most important parameter is
the good compression.
Procedure:
1.
Measure the beam size on the foil with OTR.
2.
Measure the THz energy emitted and the spectrum (with the interferometer).
3.
Measure the focal spot with the knife edge.
Time estimate: 1 hour