Cavity Update A brief history New Hardware Installed

Cavity Update • A brief history. • New Hardware Installed -- Nov 7, 2007 • Some signals exist • Test Plans -- ATLis (ACC division test plan) -- HAPPEX parasitic checks -- to be done -- January commissioning PREX Mtg, Dec 7, 2007 Bob Michaels w/ John Musson

Cavity Monitor Assembly : Measure X, Y, Q precisely Q Y X BEAM PREX Mtg, Dec 7, 2007 Bob Michaels w/ John Musson

Why do we need cavities ? 2 (i) Position Sensitivity at 10 – 50 n. A (needed for Q runs, etc) (ii) Redundant Position Measurements at the ~1 nm level !! HAPPEX 2005 Y (cavity) X (cavity) nm nm (Helicity – correlated differences averaged over ~1 day) X (stripline) PREX Mtg, Dec 7, 2007 nm Y (stripline) nm Bob Michaels w/ John Musson

Recent Improvements • 50 n. A Sensitivity – Accomplished with new firmware – Tradeoff: 5 k. Hz bandpass = “SLOW” (normally 100 k. Hz = “FAST”) – Both SLOW and FAST outputs available • Several Hardware fixes -- version was used happily by G 0. • Installed in Hall A -- Nov 7, 2007 • Thanks to John Musson’s group !! PREX Mtg, Dec 7, 2007 Bob Michaels w/ John Musson

New, Improved Firmware Signals are processed on-board, and an analog output produced for our ADCs X Signal Y Signal I Signal PREX Mtg, Dec 7, 2007 Bob Michaels w/ John Musson

Simulations of firmware predict good resolution (~1 mm in << 1 sec) at 50 n. A (maybe even ~10 n. A) PREX Mtg, Dec 7, 2007 Bob Michaels w/ John Musson

EPICS interface developed PREX Mtg, Dec 7, 2007 Bob Michaels w/ John Musson

Hot News: Current Monitor shows signs of working “FAST” Existing BCM “SLOW” PREX Mtg, Dec 7, 2007 Bob Michaels w/ John Musson

Hot News : BPMs X Slow X Fast Y Slow X Fast Rastered beam (noisy) Cavities are ready for ATLis PREX Mtg, Dec 7, 2007 (commissioning test plan) Bob Michaels w/ John Musson

Cavity Test Plans • ATLis (beam studies in Dec) -- EPICS DAQ -- Beam scan X, Y at high & low I, -- Fine - tune phase adjustment raster off and on. • Check with HAPPEX DAQ • January beam with HAPPEX & HRS DAQ’s (Dec / Jan) -- Beam scans X, Y at high & low I, -- Calibrate steering coils raster off and on. -- Measure at 50 – 1000 n. A -- Deduce Resolution and Absolute Accuracy -- Need 2 chunks of 3 hours (6 hrs total) PREX Mtg, Dec 7, 2007 Bob Michaels w/ John Musson