1. May 31, 2005Mike Hildreth – ATF 2005 Energy Spectrometry and ATF Components of the nano-BPM Test Program and Plans for Future Tests Mike Hildreth University of Notre Dame

2. May 31, 2005Mike Hildreth – ATF 2005 Spectrometry: A Reminder Required measurement precision is set by the expected statistical and systematic errors of “benchmark” measurements of m top, m higgs : –require  E beam /E beam ~ 100-200 ppm –(LEP2 achieved ~170 ppm with a combination of techniques) Spectrometer Magnet Ancillary Magnet  = 1.9 mrad 0m0m 10 m 2.5cm BPMs “upstream” “downstream” BPM-based WISRD-style

3. May 31, 2005Mike Hildreth – ATF 2005 Upstream Spectrometer Considerations “LEP-style” BPM-based Spectrometer –The only technique we could think of that gives required resolution while doing ~nothing to the beam very simple: Considerations: –Constrained by allowed emittance growth from SR –Constrained by available real estate in BDS, overall size These constraints determine needed BPM resolution/stability –Other issues drive systematic errors, diagnostics  Complicated dependence on design parameters, options –Must be robust, invisible to luminosity Ancillary Magnet  = 1.9 mrad 0m10m 2.5cm BPMs Spectrometer Magnet

4. May 31, 2005Mike Hildreth – ATF 2005 Design Decision Diagram Required BPM Resolution Chicane Length Chicane Optics (  ) d  /ds from SR Bend Radius Bend Length  (  Bd ) Mechanical Stability Beam angle jitter Betatron jitter  (bunch charge) Energy jitter Major Design parameter External constraint External input E bunch or ?

5. May 31, 2005Mike Hildreth – ATF 2005Prototype Presented at January MDI Workshop at SLAC –first attempt at an optimization within the available parameter space –Assumes 1  m BPM resolution –large, softer bends at high-dispersion point to minimize emittance growth from synchrotron radiation –will need some iteration (from things learned on this trip!) 16.1 3 3

6. May 31, 2005Mike Hildreth – ATF 2005 New BDS Optics (March) new

7. May 31, 2005Mike Hildreth – ATF 2005 Optics: details energy collimation “tail-folding” octupoles energy spectrometer chicane ΔX = 5 mm (on-energy)

8. May 31, 2005Mike Hildreth – ATF 2005 Optics: more details Δγε x = 1.2×10 -10 @ 250 GeV = 7.5×10 -9 @ 500 GeV 50  m  small beam growth due to SR high dispersion –makes measurement easier longer (~55m) –ditto Basically, meets many of the constraints on spect design (betatron phase issues while scanning B field?) Comments:

9. May 31, 2005Mike Hildreth – ATF 2005 ATF: Excellent Test Beam Many tests directly relevant to spectrometer concepts –nano-BPM tests of ultimate resolution nice, small beams to work with –“optical anchor” under construction to connect two pairs of BPM triplets –optical straightness monitor with ~10nm resolution under development –resolution and stability tests KEK nano-BPM LLNL/SLAC nano-BPM Optical Anchor

10. May 31, 2005Mike Hildreth – ATF 2005 Nano-BPM tests Overall Goal: <100nm Resolution  Stability over ~hours –Factor of 10 better than current “strawman” design –if achievable, loosens many constraints, opens many options e.g., shorter chicane, smaller bends, bunch-by-bunch E, smaller pickup motion  smaller pickup aperture, etc. Resolution: –~20nm achieved(!) –With small ATF spots (~5-10  m), but large jitter (  good test) –Can we get a 30-50  m spot at the BINP pickups? Eventually, need to show desired resolution with “ILC” spot and betatron jitter (50-100  m) if this can be done here easily, that would be a huge step

11. May 31, 2005Mike Hildreth – ATF 2005 Nano-BPM tests Stability: –~40nm achieved over 2 hours(!) In BINP pickups only –gain, phase calibration stable –(very impressive for a “first” try) –Connection with KEK BPMs needed for full system test Hopefully we can do this during the next three shifts will give first look at how complicated a “real” system will be understanding of resolutions, drifts will be critical –both BPM systems need to be understood at the same level

12. May 31, 2005Mike Hildreth – ATF 2005 Optical Monitoring Tests Optical Anchor System: –more in later talks, but 6-D measurements –Should give ~2 nm resolution in y and z (=x), more like 40nm in x –will be very interesting to give baseline numbers on absolute movements of components –cross reference with Honda-san’s Straightness Monitor  stability, and more stability how well do we need to do? What optical system is necessary? KEK BPM SLAC BPM Floor node position monitoring system is a critical component for Energy Spectrometry Planned installations will be the test bed for these systems

13. May 31, 2005Mike Hildreth – ATF 2005Conclusions ATF + ATF2 will be important test beds for all aspects of Energy Spectrometry –Test beam work necessary SOON to meet CDR time goal –Many parameters to consider –Emphasis is currently on hardware built-in redundancy will be key –in monitoring and measurement systems –Truly international collaborations “Trust, but Verify” –Beam Tests are critical for these systems tolerances are very tight, many surprises are possible –Great Opportunities here to make progress

14. May 31, 2005Mike Hildreth – ATF 2005 End Station A Test Beams T-474 (BPM Spectrometer) and T-475 (Wisrd Spectrometer) approved –will also incorporate collimator wake-field studies, other experiments concrete shielding Existing RF BPMs can be used for stability, resolution tests Beamline components scavenged from SPEAR, other SLAC surplus Nano-BPMs Goal: Demonstrate Spect performance in “real beam”

15. May 31, 2005Mike Hildreth – ATF 2005 ESA Program ESA provides “ILC-like” beam in “realistic” conditions: –Can always tweak jitter parameters to make things worse –Can “simulate” beamstrahlung pair production by using radiators –Complementary to ATF tests