SNS Harp Workshop SNS Harp Electronics Design SNS

SNS Harp Workshop SNS Harp Electronics Design SNS Harp Workshop March 13, 2003 ORNL by Mike Plum M. Plum -1 -

Signal levels from tungsten wires § If we assume: Ø Ø A dynamic range of 200 for a given profile, That we would like to measure beam profiles for beams with peak currents that can vary by a factor of 100, A factor of four safety margin for estimates of signal levels, Tungsten wire § Then: Ø Ø Need electronics for signal range of 7 n. A (7 f. C) to 8. 4 m. A (8. 4 n. C) for 25 micron diameter wire, or 32 n. A (32 f. C) to 40 m. A (40 n. C) for 100 micron diameter wire. M. Plum -2 -

Signal levels from tungsten wires (cont. ) M. Plum -3 -

Harp electronics (cont. ) § Dynamic range is a problem. § If we really want a dynamic range of 200 for a given profile, and § § want to measure beam profiles for beams with peak currents that can vary by a factor of 100, we’re talking about a dynamic range of a bit over 1, 000. Gain ranging makes the system more complicated. Can we settle for reduced measurement accuracy for low beam currents? We do this at LANSCE, and it has worked well for us. M. Plum -4 -

Harp electronics § Propose design that has been shown to work well at LANSCE: Ø Ø Integrating electronics. Gate width of a few microseconds Gate initiated by signal from ring extraction kickers. Differential input to minimize impact of electronic noise. M. Plum -5 -

Harp electronics requirements Number of channels 90 Peak signal level 8. 4 m. A (8. 4 n. C) for 25 u dia. W wire 40 m. A (40 n. C) for 100 u dia. W wire Dynamic range TBD Trigger Signal from ring extraction kicker or equiv. Linearity <1% Self test Yes Background subtraction In software M. Plum -6 -

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