MAC Review December 13-15, 2004 IR Upgrade M. Sullivan 1 Interaction Region Upgrade M. Sullivan for the Machine Advisory Committee meeting December 13-15, 2004

MAC Review December 13-15, 2004 IR Upgrade M. Sullivan 2 IR Upgrade Team J. Seeman S. Ecklund M. Sullivan M. Biagini (INFN Frascati) U. Wienands S. Gierman Y. Cai Y. Nosochkov M. Donald A. Novokhatski C. Ng S. DeBarger N. Kurita J. Langton R. Pope A. Sheng Designers

MAC Review December 13-15, 2004 IR Upgrade M. Sullivan 3 Outline Upgrade Issues Beam-Stay-Clears B1 and parasitic crossings SR power, HOM power and beam pipes Summary

MAC Review December 13-15, 2004 IR Upgrade M. Sullivan 4

MAC Review December 13-15, 2004 IR Upgrade M. Sullivan 5 Present status We have achieved  y * s of 10 mm With  x * s of 30 cm Bunch lengths are estimated to be mm Total beam currents of 2450 on 1550 (1590 on 2540 on last shift) No sign of SR backgrounds Fairly large luminosity background Total current in the support tube up to 4.1 A! Heating in the IR support tube (from Q2 to Q2) OK so far NEG pump heating by HOM power Stan will talk more about this I will talk more about this later

MAC Review December 13-15, 2004 IR Upgrade M. Sullivan 6 Issues for the near future Run 5 goals that affect the IR LER current of 3.3 A HER current of 1.8 A Higher bunch currents  more HOM power Shorter LER bunch length  more HOM power Lower  y * s to 9 mm Lower LER  x * to 30 cm Increase LER emittance to 50 nmrad Total of 5.1 A !  BSCs

MAC Review December 13-15, 2004 IR Upgrade M. Sullivan 7 Issues for the farther future Ultimate goals that affect the IR LER current of 4.5 A HER current of 2.2 A Still higher bunch currents  more HOM power Still shorter bunch lengths  more HOM power Lower  y * s to 8 mm Lower LER  x * to 30 cm Increase LER emittance to 60 nmrad Total of 6.7 A !!  BSCs

MAC Review December 13-15, 2004 IR Upgrade M. Sullivan 8 Present machine parameters LER  x * = 30 cm and LER  x = 22 nmrad LER  x * may be a little low, but it is the value for run 5 BSC just clears the present Q2 chamber on the forward side Plenty of room on the backward side BSCs

MAC Review December 13-15, 2004 IR Upgrade M. Sullivan 9 BSCs Expected LER beam size for run 5 LER parameters:  x * = 30 cm  x = 50 nmrad BSC is defined as 15  + 2mm (uncoupled) BSC violated at the septum Just enough room for the beam New chamber being built and RFI for summer 2005

MAC Review December 13-15, 2004 IR Upgrade M. Sullivan 10 BSC envelopes at the face of the Q4 magnet Present baseline design 12.5 mm Beta y* Upgrade design 7 mm Beta y* LER BSC HER BSC LER BSC HER BSC HER beampipe BSC definition: 15  + 2mm

MAC Review December 13-15, 2004 IR Upgrade M. Sullivan 11 Q5R look downbeam Q5R looking toward the IP New BSC definition: 12  x by 9  y

MAC Review December 13-15, 2004 IR Upgrade M. Sullivan 12 Q4R look downbeam Q4R looking toward the IP New BSC definition: 12  x by 9  y

MAC Review December 13-15, 2004 IR Upgrade M. Sullivan 13  Lower the vertical beta function to 7-8 mm with no IR optics hardware changes.  Maintain head-on collisions but maximize the parasitic crossing (PC) separation by changing the B1 magnets  Increase the strength of the inboard B1 slices and lower or remove the outboard slices (B1B-B1G > stronger -- last slice B1M removed)  Introduce a small crossing angle (+/- 0.5 mrad) in order to increase the PC separation  The beam energies are adjusted to help match the orbits in the crossing angle option The B1 magnet and parasitic crossings

MAC Review December 13-15, 2004 IR Upgrade M. Sullivan 14 B1 higher field If the field in the first 5 slices of B1 is increased by 30% AND the last slice is turned OFF, we get a separation at the 1st PC of 3.6 mm, that is +12% w.r.t. the design (3.22 mm) If the field in the first 6 slices of B1 is increased by 30% AND the last slice is turned OFF, we get a separation at the 1st PC of 3.77 mm, that is +17.2% w.r.t. the design from M. Biagini

MAC Review December 13-15, 2004 IR Upgrade M. Sullivan 15 # 6 Head-on B1+30% for first 5 slices, last slice OFF, old Q1, 9. x 3.1, x’= mrad LEFT SIDE LER (orbit deviation from design) LER x LER y from M. Biagini

MAC Review December 13-15, 2004 IR Upgrade M. Sullivan 16 # 6 Head-on B1+30% for first 5 slices, last slice OFF, old Q1, 9. x 3.1, x’= mrad LEFT SIDE HER (orbit deviation from design) HER x HER y from M. Biagini

MAC Review December 13-15, 2004 IR Upgrade M. Sullivan 17 # 6 Head-on B1+30% for first 5 slices, last slice OFF, old Q1, 9. x 3.1, x’= mrad RIGHT SIDE LER (orbit deviation from design) LER x LER y from M. Biagini

MAC Review December 13-15, 2004 IR Upgrade M. Sullivan 18 # 6 Head-on B1+30% for first 5 slices, last slice OFF, old Q1, 9. x 3.1, x’= mrad RIGHT SIDE HER (orbit deviation from design) HER x HER y from M. Biagini

MAC Review December 13-15, 2004 IR Upgrade M. Sullivan 19 How do we get a stronger B1  Use Nd-Fe-B  Sumitomo Neomax 35EH (12% field increase)  Radiation Hardness Heat treating the materials with higher remnant fields improves the rad-hardness at the expense of lowering B rm  Expected radiation levels in IR2 are uncomfortably close to radiation damage “knee” in APS study  Add more PM material  Design new way to clamp the magnet slices together  Design new way to get cooling water and air in and out of Be bellows

MAC Review December 13-15, 2004 IR Upgrade M. Sullivan 20 N38H used in APS study

MAC Review December 13-15, 2004 IR Upgrade M. Sullivan 21 N38H used in APS study

MAC Review December 13-15, 2004 IR Upgrade M. Sullivan 22 Radiation levels in IR2 Beam – Gas Turtle Study by Roger Barlow – /~barlow/talks/turtle/jul04.pdf –1 nTorr /A Uniform pressure –1.5 A HER current Peak bin 10 7 GeV/s near B1 –0.2 n / GeV produced isotropic –3 x 10 7 s/year – r = 2 cm distance to PM –Dose neutrons ~ 10 7 x 0.2 x 3 x 10 7 /(4 p r 2 ) = n / cm 2 / year Needs more work. Too Close to beginning of damage level 10 13

MAC Review December 13-15, 2004 IR Upgrade M. Sullivan 23 Radiation Damage to PM Materials 1kGy = 0.1 Mrad

MAC Review December 13-15, 2004 IR Upgrade M. Sullivan 24 Stronger B1 from Geometry Strength ~ log(r2/r1) –Decrease r1 Clearance to B1 chamber –Increase r2, requires thinner collar Smarter fasteners Use PM strength, rigidity after potting –Slope r2 All of this requires a new design effort

MAC Review December 13-15, 2004 IR Upgrade M. Sullivan 25 Comparisons between stronger B1s, crossing angles and energy changes The parasitic crossing separations are: Present design3.22 mm 30% Stronger B1 (Nd) mm (12-17%) Stronger B1 (volume) mm (9-21%) With +/- 0.5 mrad x angle mm (21-24%) The energy differences for the crossing angle option are: HER to (-2.5%) LER to (+2.6%) Increase the energy asymmetry AND remove last B1 slice Very preliminary look with head-on collisions: HER energy  GeV +5.1% and LER energy  GeV - 4.8%  PC separation of 3.55 mm (10%)

MAC Review December 13-15, 2004 IR Upgrade M. Sullivan 26 Luminosity versus Crossing Angle Without parasitic crossing With parasitic crossing

MAC Review December 13-15, 2004 IR Upgrade M. Sullivan 27  Synchrotron radiation masking has been checked OK with a 7mm beta y*  Beam-gas and coulomb should be essentially unchanged since the geometry is almost the same and the masking is the same. These backgrounds should slowly improve as the total number of A-hrs increases  Radiative Bhabhas as a background that increases as the luminosity increases Detector backgrounds

MAC Review December 13-15, 2004 IR Upgrade M. Sullivan 28

MAC Review December 13-15, 2004 IR Upgrade M. Sullivan 29

MAC Review December 13-15, 2004 IR Upgrade M. Sullivan 30  Most HER chambers are OK (N. Kurita)  HER beam pipes in Q4 and Q5 (R. Pope)  Most LER chambers are OK (N. Kurita)  LER beam pipes next to Q4 and Q5 (J. Langton)  HOM power near the IP (S. Ecklund)  HOM power and NEG pumps (M Sullivan) SR power, HOM power and beam pipes

MAC Review December 13-15, 2004 IR Upgrade M. Sullivan 31  The IR upgrade is still looking at modifying the B1 bending magnets to improve the beam separation at the 1 st parasitic crossing while maintaining head-on collisions. The inboard slices are made stronger and the outboard slice(s) are removed to maintain the present beam orbits. Stronger magnetic material is needed to do this. However, we have not found a material that is comfortably rad-hard.  The option of adding a small crossing angle (+/- 0.5 mrad) using the present hardware can be done by changing the beam energies by about +/- 2.5%.  All new beam orbits are within 2 mm of the present design orbits  The rest of the IR magnets are unchanged  The original HER BSC definition in the QD4 magnet is too large for the beam pipe and the magnet apertures when we go down to 7-8 mm beta y* values. We have subsequently redefined the BSC so that new chamber designs can progress Summary

MAC Review December 13-15, 2004 IR Upgrade M. Sullivan 32  The present SR mask design is adequate for shielding the detector Be beam pipe from the SR fans. The present design constraint of not allowing any photons to strike a surface where they can one-bounce to the Be beam pipe is being preserved.  The same geometry means that the SR power distribution is almost exactly the same as the present design. The increased power levels from the SR fans mostly comes from the higher beam currents  The high beam currents and the shorter bunches will generate a lot more HOM power. We have already seen effects of this in the NEG pumps located in the IR straight and several other points bear watching  The IR upgrade work is progressing. Engineering and designing efforts have begun in earnest. Summary cont.