June 15-17, 2004DOE Operations Review of PEP-II/BaBar1

M. Sullivan

for the PEP-II Team

DOE Operations Review of the PEP-II B-Factory

June 15-17, 2004

PEP-II IR Upgrades

June 15-17, 2004DOE Operations Review of PEP-II/BaBar2

Outline

• Present Interaction Region

• Present Status

• Upgrade plans

• Plans for summer 2004 and summer 2005

• Summary

June 15-17, 2004DOE Operations Review of PEP-II/BaBar3

PEP-II Interaction Region

e+e- eeLuminosity signal

June 15-17, 2004DOE Operations Review of PEP-II/BaBar4

LER Synchrotron Radiation Fans

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HER Synchrotron Radiation Fans

June 15-17, 2004DOE Operations Review of PEP-II/BaBar6

PEP-II Interaction Region and the BaBar Detector

HER

LER

Collision point

BaBar

e e

June 15-17, 2004DOE Operations Review of PEP-II/BaBar7

PEP-II Upgrade Plans

• Lower y* from 10.5 to 8mm

• Increase number of bunches to 1720• Raise LER beam current from 2.4 to 4.5 A

• Increase LER bunch current from 1.6 mA to 2.6 mA

• Raise HER beam current to 1.4 to 2.2 A• Increase HER bunch current from 1.0 mA to 1.3 mA

• Shorten bunch lengths to 9 mm

• Reach peak luminosity by Summer 2007

• Increase luminosity to 2.41034 cm-2 sec-1

June 15-17, 2004DOE Operations Review of PEP-II/BaBar8

Overall Parameters and Goals

Parameter Units DesignBest in collision

Future 2007 goal

I+ mA 2140 2450 4500

I- mA 750 1550 2200

Number bunches

1658 1588 1715

y* cm 15-20 11 8

y 0.03 0.05, 0.08 0.055-0.08

Luminosity x1033 3.0 9.2 24

Integrated lumi / day

pb-1 130 710 1800

Over 5 designOver 3 design

2 design

2 design

3 design

½ design

8 design

Over 13 design

June 15-17, 2004DOE Operations Review of PEP-II/BaBar9

Upgrade Current & Energy Requirements

  Current (A)Energy (GeV) SR power

LER - Main Ring      

Design Limit 3 3.5  

FY2005 Goal 3.6 3.1 Less than design limit

FY2007 Goal 4.5 3.1 Less than design limit

HER - Main Ring      

Design Limit 3 9  

FY2005 Goal 1.8 9 Less than design limit

FY2007 Goal 2.2 9 Less than design limit

Interaction Region (IR)      

LER Beam Power      

Design Limit 3 3.1  

FY2005 Goal 3.9 3.1 22% SR power increase

FY2007 Goal 4.5 3.1 50% SR power increase

HER Beam Power      

Design Limit 2 9  

FY2005 Goal 1.8 9 Less than design limit

FY2007 Goal 2.2 9 10% SR power increase

June 15-17, 2004DOE Operations Review of PEP-II/BaBar10

Upgrade PlanOther Requirements

• Increased HOM Heating, RF shielding

– Bunch Length• 2004: 11-12 mm• 2006: 9 mm

– Bunch Current• LER 45% increase• HER 30% increase

• New Lattice

– IR Lattice and BSC

June 15-17, 2004DOE Operations Review of PEP-II/BaBar11

IR Modifications• We think we can get to 8 mm y* without any major hardware

changes in the near IR. We have achieved these y*s in machine

development days, which is encouraging. However, we still have a lot of work to do to make these lower y* values perform.

• Vacuum chamber heating from SR power at the higher beam currents is being re-evaluated for all of the chambers in the IR. For the chambers inside +/- 3 m of the IP things look OK.

• SR masking for detector backgrounds is OK

• We presently see some beam-beam effects from the 1st parasitic crossing in the by2 pattern, 63 cm from the IP. Presently, we can correct for most of this effect and get back the lost lumi. This parasitic crossing effect is made worse with lower y*s. Will we still be able to compensate?

• We want to maintain head-on collisions but keep open the option of introducing a small crossing angle at the collision point.

June 15-17, 2004DOE Operations Review of PEP-II/BaBar12

IR modifications (cont.)

• Looking at upgrading B1 magnets to improve the 1st parasitic crossing effect

• Keep the Bdl the same. Strengthen the inside magnetic slices and weaken or remove some of the outside slices.

• Need a rad hard magnetic material with a higher field strength

• We want to build new radial ion pumps. The present pumps are not working.

• Build new HER Q5 chambers and possibly new Q4 chambers

• Rebuild some of the LER vacuum chambers with NEG pumps (inadequate RF screens)

June 15-17, 2004DOE Operations Review of PEP-II/BaBar13

Modifications in the support tube

Replace pumps

Silicon vertex tracker

June 15-17, 2004DOE Operations Review of PEP-II/BaBar14

New orbits almost the same as present machine

Keep new design orbit within 2 mm of present design

June 15-17, 2004DOE Operations Review of PEP-II/BaBar15

B1 Radial Ion Pump

RF screenRF screen

New BPM setNew BPM set

• Issues– Argon Instability

– Both pumps are non-functional

• Status– Progressing on schedule for

2005 installation

– New pump design near completion

– Changed to a noble diode pump

• rebuild with tantalum plates

– Split pump into two circuits

– Added BPM set with the correct separation to decipher the position of the two beams

– Replaced feedthru with a standard pump feedthru

Baffles to Baffles to prevent SR prevent SR scatter hitting scatter hitting pumppump

Example of work in progress

June 15-17, 2004DOE Operations Review of PEP-II/BaBar16

Q1/Q2 HOM Bellows• Issue

– HOM Power• Absorbing ~10 KW presently• Predict ~ 50 KW in 2007

• Status– Using MAFIA optimizing a

design solution • Tiles need to absorb HOM

power, without creating excessive HOM power.

• Significant amount of the power it absorbs is created by the beam passing by it.

– Plan to build a test bellows this fall and replace an existing bellows in a straight section with trapped HOM power.

June 15-17, 2004DOE Operations Review of PEP-II/BaBar17

Summary of Rebuild Plans• Summer/Fall 2004

– Synchrotron Light Monitor (SLM)– Pin Hole Camera Version

– Frascati style Transverse Kicker

– Longitudinal Feedback Kicker

– RF cavities– New support tube chiller

• Summer/Fall 2004 – pending improvements– Q1/Q2 HOM test bellows– New gasket style ion pump

screens– Q5 temporary chamber– LER IR2 NEG chambers

• Summer/Fall 2005 – pending improvements – Q2L Chamber– HER and LER Q4 and Q5

chambers– Stronger B1 magnet– Radial Noble Diode Ion Pump– Vertex Bellows– Q1/Q2 HOM Bellows– Q4/Q5 Bellows– 10m Fixed Collimator in HER

June 15-17, 2004DOE Operations Review of PEP-II/BaBar18

Contributers/ Upgrade Staff

• Physicists– Michael Sullivan– John Seeman– Stan Ecklund– Sasha Novokhatski– Uli Wienands– Cho K. Ng– Keith Jobe– Mark Ross– Artem Kulikov– Alan Fisher– Daniel Wright

• Designers– Catherine Carr– Don Arnett– Ben Smith– Ben Bigornia– Ken Banuelos– Manual Trigos– Ho Dong– Ted Osier

• Engineering– Scott Debarger– Nadine Kurita– J Brian Langton– Rodd Pope– Albert Sheng– Stewart Metcalfe– Mohammad

Dormiani– David Kharakh

June 15-17, 2004DOE Operations Review of PEP-II/BaBar19

Conclusions

• We have a small but very dedicated staff

• We are in the process of identifying hardware that will limit future machine performance

• Working on hardware upgrades for both this coming summer 2004 and for summer 2005

• We have several meetings each week to address various issues:

– Tue vacuum – present status and upgrade progress

– Wed vacuum – specifically for upgrade designs

– Fri IR upgrade – all aspects of the IR upgrade

– Fri bkgds – present and future projections of detector bkgds

• Near term upgrades are going well

• Planned upgrades toward a luminosity of 2.41034 are on track