arXiv subjects

P. Forck

Publications and source records attributed to P. Forck.

4 recordsLinked to original sources

arXiv2012

Interpretation of transverse tune spectra in a heavy-ion synchrotron at high intensities

Two different tune measurement systems have been installed in the GSI heavy-ion synchrotron SIS-18. Tune spectra are obtained with high accuracy using these fast and sensitive systems. Besides the machine tune, the spectra contain information about the intensity dependent coherent tune shift and the incoherent space charge tune shift. The space charge tune shift is derived from a fit of the observed shifted positions of the synchrotron satellites to an analytic expression for the head-tail eigenmodes with space charge. Furthermore, the chromaticity is extracted from the measured head-tail mode structure. The results of the measurements provide experimental evidence of the importance of space charge effects and head-tail modes for the interpretation of transverse beam signals at high intensity.

physics.acc-ph↗

arXiv2000

Commissioning of Ih-RFQ and Ih-DTL for the Gsi High Current Linac

The new 1.4 MeV/u front end HSI (HochStromInjektor) of the Unilac accelerates ions with A/q ratios of up to 65 and with beam intensities in emA of up to 0.25 A/q. The maximum beam pulse power is up to 1300 kW. During the stepwise linac commissioning from April to Septem-ber 1999 the beam behind of each cavity was analysed within two weeks. A very stable Ar1+ beam out of a vol-ume plasma source MUCIS was used mainly. The meas-ured norm. 80 % emittance areas around 0.45 pi mm mrad are close to the results from beam simulations. Up to 80 % of the design intensity at the linac exit were achieved. In February 2000 an U4+ beam from the MEVVA source was accelerated for the first time.

physics.acc-ph↗

arXiv2000

Measurement of the six Dimensional Phase Space at the New GSI High Current Linac

For the characterization of the 10 mA ion beam delivered by the new High Current Linac at GSI, sophisticated, mainly non-intersepting diagnostic devices were developed. Besides the general set-up of a versatile test bench, we discuss in particular bunch shape and emittance measurements. A direct time-of-flight technique with a diamond particle detector is used to observe the micro-bunch distribution with a resolution of $\sim 25 $ ps equals 0.3$^{o}$ in phase. For the determination of the energy spread a coincidence technique is applied, using secondary electrons emitted by the ion passing through an aluminum foil 80 cm upstream of the diamond detector. The transverse emittance is measured within one macro pulse with a pepper-pot system equipped with a high performance CCD camera.

physics.acc-ph↗

arXiv2000

The New Gas Stripper and Charge State Separator of the Gsi High Current Injector

The GSI Unilac was upgraded as a high current injector for the SIS in 1999. Therefore, the stripping section [1] at 1.4 MeV/u, where a beam transport under highest space charge conditions and multi beam operation had to be established, was completely new designed. Results of the commissioning of the stripper section will be presented. The beam transport to the new gas stripper, and the charge state analysis under space charge conditions confirmed the calculations. A 238U4+ beam - coming from a MEVVA ion source and accelerated by the new injector linac- was stripped (with the expected stripping efficiency) to the charge state 28+ and successfully separated by the new spectrometer (15 degree and 30 degree kicker magnets). The transport and matching to the poststripper accelerator under highest space charge conditions was investigated with a 15 emA 40Ar10+ beam. Especially space charge and charge state dependent emittance growth effects in 6d-phase space will be discussed.

physics.acc-ph↗