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Main Injector Lambertson Aperture Scans. David Johnson and Ming-Jen Yang March 17, 2006. Motivation and Data Collection. The goal is to document the loss free apertures through the Main Injector Lambertson regions prior to the installation of the WQB wide aperture quads.
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Main Injector Lambertson Aperture Scans David Johnson and Ming-Jen Yang March 17, 2006
Motivation and Data Collection • The goal is to document the loss free apertures through the Main Injector Lambertson regions prior to the installation of the WQB wide aperture quads. • The expected increase in circulating beam aperture in the Lambertson regions is due to: • the increase in beam pipe dimensions of the WQB on the inside of the ring, • the shifting of the Lambertson septa to the radial outside (which will also require new Lambertson flanges and the re-alignment of the upstream end of the transfer line. • The wide aperture quad (4”) will allow the extracted beam to be farther to the outside of the ring without loss on the quad pole tip.
MI-52 Loss Monitor Placement LN520E (61-45)* LM520A (61-0) LN520C (61-2/2)* LN520B (61-1) LN520D (61-3/4)* ES52B ES52A K520A,B Q521 Q520 LN522A (61-7/7)* LN521B (61-6/6) * LM521A (61-5) LAM52A H522 TAR521 Q522 Q521 LM522D (61-10) LM522E (61-11) LM522B(61-8) LM522C(61-9) LM523 (62-3) LM522G (62-1) LM701 (P1) LM522H (62-2) LM522F (62-0) Q701 V701 LAM52C LAM52B Q523 Q522 *Goes to chassis 2 w / beamline integrators – reset / hold timers I:LMNUMR and I:LMNUMH The numbers in parenthesis are the house - slot number and the number after the “/” is the slot in crate 2
MI-60 Loss Monitor Placement Around NuMI Lambertsons LM on Lambertson Flange LAM60 – NuMI Loss Monitors LM607A(63-7) LM on conduit LM608 B(63-10) LM607B(63-8) LM608A(63-9) LAM60A H608 RF cavities Q608 Q607 LAM60 LM608 G(64-3) LM608 C(63-11) LM608 F(64-2) LM608 H(64-4) LM609(64-5) LM608 E(64-1) LM608 D(64-0) LAM61A LMQ608 V100 Q101 V101 LAM60C LAM60B Q609 Q608 LAM61B Q101
MI-62 Loss Monitor Placement LM619A (64-3) LM619B (64-4) LM619E (64-7) LM619D (64-6) LM619F (64-8) LM620A (64-9) LM619C (64-5) LAM60B LAM60C V101 Q101 Q620 Q619 LM620C (64-11) LM620D(65-0) LM620B (64-10) LM621 (65-1) pbars LAM60A H620 Q620 Q621
Data Collection • Injection scans were performed using a dedicated 8 GeV $2E cycle. • Extraction scans (MI52 and MI60) were performed on low intensity stacking and NuMI cycles. • First turn data was taken by aborting the beam after only one pass thru the Lambertson region of interest. The loss monitor “sample and hold” event, $2C, was set to measure the peak of the loss monitor response. • Data on beam intensity, positions, loss and magnet currents were taken using I90. • Data was transferred to excel for data analysis
Expectations • What apertures are expected through Lambertsons? • Field Free: 60 mm loss free (1/2 MI beam pipe if septum edge is located on MI centerline) • Field Region: 50 mm loss free (on axis) due to 50 mm field region aperture. Expect first loss on outside of ring to occur on the Lambertsons either side of the quad • What aperture is expected vertically in MI beam pipe? • The inside dimension of MI beam pipe is ~47mm • For 20 p and b = 55m, 6s = 26.4 mm => +/-10.3mm free aperture
Summary of Aperture Scan Data Sets • MI40 8 Gev • Horizontal scan Field and Field Free region with 1st turn H402:3 • Vertical scan of Field Free close to notch (V401:4) • Horizontal scan of Field region (only toward septum) K400 • MI52 8 Gev • Horizontal scan Field region with 1st turn KPS5S • Horizontal scan Field Free circulating using H522:3 • Horizontal scan Field Free and Field region 1st turn using H522:3 • MI52 120 Gev • Horizontal scan Field Free region using H522:3 • Vertical scan of Field Free region using V521:4 • Horizontal scan of Field region using KPS5S and H522:3 • MI60 8 Gev • Horizontal scan Field Free region 1st turn H608:3 • Horizontal scan Field Free (and Field) region 1st turnH608:3 • MI60 120 Gev • Horizontal scan Field region KPS6S • Horizontal scan of Field Free region (only toward septum) circulating H608:3 • MI62 8 Gev • Horizontal scan Field Free (and Field) region 1st turn H620:3
Summary of LAM40 Scan • Assume 10 p beam • 8 Gev First turn using protons (060201) • Field Free Region • Centroid of 8 Gev beam at HP402 is -27.8 mm • Inside loss start -41.3 mm on HP402 as seen on LM402G • Loss on septum starts at -11 on HP402 or +16.8 mm motion from the nominal • Loss free aperture ~30 mm+ 16mm beam size -> ~46 mm • Field Region • Beam strikes loss monitors LM402F,G,and H septum first on both sides of the field region • The edge of loss free region based upon the upstream loss monitors is 33.6 and 57.6 which gives a width of 24 mm + beam width which would eb ~ 40 mm
Summary of LAM52 Scans • Assume 10 p beam ,then 6 s would be ~16 mm at entrance to 1st Lambertson • Calculate aperture relative to position at entrance to first Lambertson HP_LAM52A • 8 Gev First turn Field Free (060130) • Centroid of 8 Gev beam is -22.7 mm at LAM52A • Inside loss start -44 mm on beam pipe • Outside loss starts -6 mm on septum • Loss free aperture 38 mm + beam size (~16mm)-> ~ 54 mm • 8 Gev Circulating Field Free (060131) • Inside loss starts at -39 mm • Outside loss (septum) first loss -12 mm • Loss free aperture 24 mm + beam size (~16mm) -> ~40 mm • 120 Gev Field Free(060223) • Centroid circulating beam -13 mm • First loss seen on LM522A at -1.65 mm • No loss seen on inside beam pipe • Vertical scan
Summary of LAM60 Scans • Assume 10 p beam • 8 Gev First turn Field Free (060130) • Centroid of 8 Gev beam is -32 mm • Inside loss start -46 mm beam pipe • Outside loss starts -14 mm on septum as seen by LM608F • Loss free aperture 24mm+beam size -> ~37mm • 8 Gev First Turn Field Free (060131) • Inside loss starts at -40 mm • Outside loss (septum) first loss -18 mm • Loss free aperture17mm+beam size (~16mm) -> ~34mm • 120 Gev Field Free and Extraction (060223) • Centroid circulating beam -23 mm • First loss seen at -3 mm • Centroid of extracted beam +17.5 mm • First loss seen on LM608A at 11.4 mm
Position of 120 Gev Beam at HP608 Sigma 20 p ~ 1.2 mm Shows a movement of 5mm
Summary of LAM62 Scan • 8 Gev First turn using protons (060201) Assume 10 p beam • Field Free Region • Centroid of 8 Gev beam at HP620 is -35.5 mm • Inside loss start -52 mm on HP620 as seen on LM620A and B • First loss seen on LM621 moving toward seputm at -19 mm on HP520 followed by LM620D with LM619C • Loss free aperture 30 mm + 23 beam size -> ~53 mm • Field Region • Lambertsons on at 8 Gev level-> bend protons up to hit the pole tip of Q620 which saturate loss monitors close to quad and raises background due to backscatter on loss monitors farther upstream • When scanning from field region toward the septum, the beam strikes LAM62C septum first due to septum offsets • Loss free width on LM619D is 21 mm followed by LM619E (both on LAM62C) and then on LM619C is 25 mm + beam size • Loss on LM619C is back scatter. This loss monitor is not saturated and will be used to estimate beam size • Beam Size Comments • Based upon beta at upstream end of LAM62C (28m) the sigma for a 10 p should be 2.2 mm and 6 sigma should be 13.2mm. • Use the non saturated LM619C loss monitor to estimate beam size by scanning the beam across the septum of LAM62C. • Beam extends to about 21 mm full width which gives a 11.5mm half width which implies beam extends out to 5.3 s.
Cartoon of LAM62 Layout LM620B LM620A LM619D LM620D LM619C Q620 LAM62C LAM62B LAM62A 5mm 2.54mm PBARS p Field free region
protons Circulating Field Free Region Pbars Q622 Q618 Q620 Extraction Field Region
Cross Section at Q608 Start loss with circulating beam Start loss with single pass beam Assume 10 p s ~ 3.1 mm Beam out to about 6.5 s on circulating beam Beam out to ~ 4.5 s on 1st turn beam +/-3 sigma beam at nominal HP608 position