Laser synchronized subpicosecond pulse radiolysis

Figure 11 The components of the timing jitter of the laser synchronized subpicosecond pulse radiolysis, crj is the length of the electron pulse (rms), c,- is the length of the probe light (rms), and ctj is the timing fluctuation (rms).

The new accelerator at Brookhaven is based on an RF photocathode gun with one or more resonant cavities in which microwaves create transient electric fields up to 1 MeV cm [104], A pulse of laser light is used for generating photoelectrons which are accelerated to 9 MeV in a distance of 30 cm. The laser pulse can also be used as the analyzing light source this means it is closely synchronized with the electron pulse. The time resolution of the electron pulse is therefore that of the laser pulse, so that subpicosecond pulse radiolysis is possible. A similar system is planned at Argonne National Laboratory [146],... 

Access to subpicosecond electron pulses has already been achieved at Osaka University by a new double-decker accelerator concept. In order to reduce the time jitter for the detection of the optical absorption signals in pulse radiolysis studies, the light pulse used for the pump-probe system is Cerenkov emission which is produced in the same cell by a synchronized second electron beam and is concomitant with the electron path. The distance between the axes of the two beams is 1.6 mm. The pulse durations of these electron pulses, which are both produced by delayed beams issued from the same laser, are 430 + 25 fs and 510 20 fs, respectively, and the charge per pulse is 0.65 nC. An electron bunch of 100 fs and 0.17 nC has already been generated. 

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