# Presentation: 761375

## What I’ve been doing for many of the days you haven’t seen me here

- Bill Ashmanskas
- Nov 25, 2003

## First things first ...  a shameless plug

- PR D68 091101

- physics/0306169

- But since August, when this stuff was finished, I’ve joined
- Bill Foster’s ongoing damper board effort for Run II

## Bill Foster’s damper board team includes

- Bill Foster
- Dave Wildman
- Dennis Nicklaus
- Alexei Seminov
- Warren Shappert

- Sten Hansen
- Terry Kiper

- Bill Ashmanskas
- Eric James

- FNAL/BD
- PPD engineering
- ANL/CDF
- FNAL/CDF

## Outline

-  What is a “damper” anyway?
-  What does this damper look like?
-  How have I been able to help out so far?

## What does a damper do?

- Detect coherent bunch oscillation w.r.t. stable orbit and apply a kick to correct it
- Correct for injection errors (x,x’,y,y’,,E) before beam filaments (emittance growth)
- Counteract instabilities before they grow out of control
- Do this for horizontal, vertical, and longitudinal coordinates

## Transverse motion w.r.t. stable orbit (cartoon)

## Many particles, with their own small excursions

## Steering error  bunch centroid oscillates

## If coherent motion isn’t corrected, nonlinearities cause beam to decohere, fill larger phase space

## Transverse damper at work (GWF, Lehman review)

## Transverse damper at work (GWF, Lehman review)

## Transverse damper at work (GWF, Lehman review)

## Transverse damper at work (GWF, Lehman review)

## Transverse damper at work (GWF, Lehman review)

## You can see that damper project has merit
The longitudinal damping is now under test, and should yield results that are more impressive
Results I showed are from before I joined (except that I helped with the late-2002 prototyping)

Key point: This is work to which CDF electronics types can readily contribute (familiar hardware)

I’ve been helping Bill F to commission the second-generation damper boards, which arrived in July 2003

- The longitudinal damping is now under test, and should yield results that are more impressive
- Results I showed are from before I joined (except that I helped with the late-2002 prototyping)
- _Key point_: This is work to which CDF electronics types can readily contribute (familiar hardware)
- I’ve been helping Bill F to commission the second-generation damper boards, which arrived in July 2003

## Bill Foster’s damper concept

- (or VME,
- VXI, PCI,
- etc.)

## What the FPGA computes

## Relevance of CDF experience: this isn’t so scary ...

- once you’re used to working with this

## Prototype damper (kludged commercial board)

## New board being commissioned

## In-house damper board, by A. Seminov

- One Altera Stratix 1S30 (vs 5 separate older Altera chips on commercial board)
-  much more straightforward to program
- 212 MHz ADCs (vs interleaved 106 MHz pairs)
- 424 MHz DACs (vs 212 MHz on daughter card)
- On-board CPU+ethernet for configuration and ACNET interface (vs VME + JTAG cable)

## So far, I’ve been mainly working on the configuration & readout path for the new board (because Alexei is stuck in Russia!).  Good progress: e.g. can configure stand-alone board via TCP/IP, have established communication with Dennis Nicklaus’s ACNET interface.

- Meanwhile, Eric (the other CDF guy) and Warren are showing that this board could work for Tevatron BPM readout.

## Same board can do BPM readout!

## Summary

- Once I got my CDF papers out, I decided that the most useful thing I could do was to try to help Bill F with his damper board
- People with HEP trigger/DAQ experience should not have much trouble finding a way to contribute
- The same programmable-chip technology that has had a big impact on the CDF trigger can be readily applied to all sorts of beam measurement/feedback/control