1. W. KozaneckiMCC AP meeting, 24 Apr 06 Slide 1 Using the gas-induced beam blowup to measure vertical IP beam sizes  Principle  heat NEG @ PR02 VP8020  @ constant beam currents, using NEG heater  sufficiently to cause vertical HEB blowup… ..but not enough to induce a transverse instability  simultaneously monitor  pressure @ VP8020, BBR backgrounds  beam currents  L sp, HER & LER SLM/interf spot sizes   x L,  ' x H,  ' y H (  ~ 30' of data taking) W. Kozanecki

2. MCC AP meeting, 24 Apr 06 Slide 2 Serendipitous measurement on 20 Apr 06

3. W. KozaneckiMCC AP meeting, 24 Apr 06 Slide 3

4. W. KozaneckiMCC AP meeting, 24 Apr 06 Slide 4  L sp,1 ~ c L /  y,1   y,1 =   y+ +   y- =   y+ (1 + R *2 y ) L sp,2 ~ c L /  y,2   y,2 =   y+ +   y- =   y+ (1 +  R *2 y ) L sp,2 ~ c L /  y,2   y,2 =   y+ +   y- =   y+ (1 +  R *2 y ) where  = (  interf y,2 /  interf y,1 ) 2 assumes that   y- /  interf y = constant  Define f L = (L sp,1 / L sp,2 ) 2 then R * 2 y = (1 - f L ) / (f L -  ) In this example, In this example, L sp,1 = 3.3, L sp,2 = 3.0,  interf y,1 =.270,  interf y,2 =.325, R * y = 0.94 Extracting the ratio R* y =  * y- /  * y+

5. W. KozaneckiMCC AP meeting, 24 Apr 06 Slide 5 Consistency checks & improvements  If the HEB blowup (before instability) is due to beam-gas scattering (simple emittance increase) rather than an ion instability, then  the effect should occur at low current at a comparabel pressure  it should be reflected in the  y 'H measurement from the boost  the same technique might work by injecting a gas bump in the LER  The result presented here is very rough (#s read off history plot, currents not constant all the way): need a cleaner dataset, I.e. a controlled experiment, where we also monitor all the beam sizes (HB: no large change seen in other 3 SLM sizes: HER x, LER x, y)  If  y can be measured directly, e.g.  by boost method (~1 week of data)  from L sp (direct, absolute) &  x using SLX/M's in both rings (AB, AF)  at low current, using beam-beam scans then we can measure separately  * y- and  * y+ then we can measure separately  * y- and  * y+