Doug is correct about the optimum dump current. In fact, there is
an elog entry (28476) about it from 9/1. Don't people read the elog??? I
admit, the title of the entry is about ramp rates, but the text clearly
associates the increased ramp rate with a change in the optimum dump current.
Please READ the logbook regularly, and MAKE ENTRIES with any
changes and observations. It is there to communicate information across
shifts, detail problems and their solutions, and make life easier down the
road for those trying to do analysis.
Karen
At 01:10 AM 9/4/2004 -0400, Douglas Hasell wrote:
>Last week, Michael, Karen, and I increased the ramp rates on the HV for
>the WC and LADS from 100 V/s to 200 V/s. This had the affect of
>shortening the deadtime when filling the ring. Consequently the current
>at which we should dump the beam is higher than normal. I suspect that
>for 140 mA injection that we should be dumping at 95 mA for optimal luminosity.
>
>To calculate the optimal current use the equation:
>
> I_dump = I_inject * exp( -t_live / tau )
>
> there I_dump and I_inject are obvious, tau is the average beam
> lifetime and t_live is the live DAQ time for each fill as calculated by:
>
> t_live = SQRT( 2 * t_dead * tau )
>
>where t_dead is the deadtime during a fill from the time when the DAQ
>stops until it starts again. Currently I think t_dead is around 1.5
>minutes, tau is around 20 minutes thus t_live should be 7.75 minutes and
>i_dump is 68% of i_inject.
>
>
> Cheers,
>
> Douglas
>
>26-415 M.I.T.
>Tel: +1 (617) 258-7199
>77 Massachusetts Avenue Fax: +1 (617)
>258-5440
>Cambridge, MA 02139, USA E-mail: hasell@mit.edu
>
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