49th ICFA Advanced Beam Dynamics Workshop49th ICFA Advanced Beam Dynamics Workshop

October 8 –12, 2010October 8 –12, 2010Bunch By Bunch Instrumentation Upgrades For CESR Based On Requirements For The CESR Test Accelerator Research Program

N.T. Rider, D.P. Peterson, J.P. Alexander, M. G. Billing, C.Connoly, N.Eggert, E.Fontes, W.Hopkins, B.Kreis, A.Lyndaker, R.E. Meller, M.A. Palmer, M.C. Rendina, P.Revesz, D.L. Rubin, J.Savino, R.Seeley, J. Shanks, C.R. StrohmanCLASSE, Cornell University, Ithaca, NY 14853, U.S.A.R.L. Holtzapple California Polytechnic State University, San Luis Obispo, CA 93407, U.S.A.J.W.Flanagan KEK, Japan

Property Specification

CESR Instrumentation Support BPM DevelopmentAbstract

J.W.Flanagan KEK, Japan

The research focus of the CESR TestAccelerator program requires newinstrumentation hardware, software andtechniques in order to accurately investigate

PropertyFront-end Bandwidth (4ns bunch trains)

Absolute Position Accuracy (long term)

Single Shot Position Resolution

Specification500 MHz

100 µm

10 µm

•C Based control code

•Supports multiple instrument types

Instrument control GUI

and analysis toolstechniques in order to accurately investigatebeam dynamics in the presence of electroncloud effects. These new instruments arealso required to develop low emittance beamconditions which are key to the success of

Single Shot Position Resolution

Differential Position Accuracy

Channel-to-Channel Sampling Time Accuracy

BPM Tilt Errors (after correction)

10 µm

10 µm

10 ps

10 mrad

and analysis tools

conditions which are key to the success ofthe damping ring design for the InternationalLinear Collider. This poster will detail someof the architecture and tools which have beendeveloped to support these efforts.

BPM Tilt Errors (after correction) 10 mradExperiment

Specific

Instruments

•Server/client code

•Multi Language Functions

•Lab wide networking

•Hardware interface designs

developed to support these efforts.Emphasis will be placed on the 4 ns bunchby bunch Beam Position Monitoring systemas well as the 4 ns capable X-ray Beam SizeMonitor.

•Online/Offline data storage

•Automatic archiving

Monitor.

•Multi Language File Input/Output Routines

•Standardized Data Format

•Communication and Command Functions

XBSM Tools and Analysis

•Communication and Command Functions•Data collection synchronization

•Programmable triggers

•Encoded phase information

Low level

communications

XBSM Tools and Analysis

Positrons ElectronsElectrons

At this stage of the program, the electron instrument is now basically operational. Efforts have focused on amplifier and digitizer development. This instrument uses the new 4 ns digitizer and corresponding amplifiers. Software tools have been created using Matlab which allow for basic corresponding amplifiers. Software tools have been created using Matlab which allow for basic imaging and fitting operations.

All three optics elements have been imaged. Basic fitting has been applied to the pin hole data. The fits have been used to actively tune the beam conditions.fits have been used to actively tune the beam conditions.

The basic characteristics of the electron optics are the same as the positron instrument, with the exception of the dimensions of the Coded Aperture. The Coded Aperture used on the electron instrument is 155 µm x 500 µm.

The electron instrument has been used to demonstrate the

instrument is 155 µm x 500 µm.

been used to demonstrate the successful operation of the new digitizers and the clean separation of 4ns spaced bunches.

The image of the Fresnel Zone Plate is a diffraction pattern and sensitive to the x-ray wavelength. There is a central peak due to designing the x-ray beam and FZP to focus at

The vertically limiting slit operates as a pin-hole lens. The slit has been adjusted to be about 16µm in height, which gives the minimum image width. A smaller slit height

The image of the Coded Aperture is a combination of transmission and diffraction resulting from the 8 slits ranging in size from 10 to 40µm (positron line).

Advantage: bunches.designing the x-ray beam and FZP to focus at the maximum of the x-ray wavelength distribution.

Disadvantage:The image shown is without the use of a

minimum image width. A smaller slit height would cause the image to broaden due to diffraction while a larger slit height would cause the image to broaden due to transmission.

Advantage:As in the case of the vertically limiting slit, the imaging is relatively insensitive to variations in the wavelength. The resolving power of the CA has been compared to that of the FZP, both without the Matlab Based ToolsThe image shown is without the use of a

monochromator; it has a broad underlying distribution of out-of-focus x-rays. Use of a monochromator eliminates the broad component but does not allow enough x-ray flux for useful

transmission.

Advantage:It is largely insensitive to the x-ray wavelength within the synchrotron radiation spectrum.

been compared to that of the FZP, both without the use of a monochromator. Data was collected in “slow scans” for the two imaging devices, for two beam sizes. For each imaging device, the RMS of the difference between images from different beam

Matlab Based Tools

but does not allow enough x-ray flux for useful turn-by-turn measurements.

Advantage:The central peak of the image shown provides

spectrum.

Disadvantage:While the pin-hole provides a simple peak, the image is a convolution of the beam

the difference between images from different beam sizes is an indication of the resolving power. The RMS difference for the CA was 1.7x greater than that of the FZP (for the same change in beam size and normalized for incident photon flux), indicating

The central peak of the image shown provides useful beam size measurements to the smallest beam size. Turn averaging and fitting procedures to extract this information have been developed.

height and the slit height resulting in large uncertainties for beam size measurements below about 16µm.

and normalized for incident photon flux), indicating that the beam size resolving power of the CA is superior.

A Challenge:developed. A Challenge:In the future, we will develop the template based fitting procedure necessary to exploit the improved resolution.

Vertically Limiting Slit (Pinhole) Coded Aperture Fresnel Zone Plate

XBSM Hardware

Synchrotron radiation x-rays are emitted in a dipole magnet (not shown).

Hole, for calibrationshown).

Coded Aperture

Hole, for calibration

4 ns Pre Amplifier

Fresnel Zone Plate

Separate xBSMs are successfully commissioned in x-ray beam lines to measure + The FZP and CA are manufactured on a common commissioned in x-ray beam lines to measure the sizes of the electron and positron beams. The positron line is illustrated here.

+ The FZP and CA are manufactured on a common silicon substrate. For the positron line, the patterns are cut into 0.7µm Au and are supported by a 2.5µm Si membrane. The FZP pattern has 120 transmitting rings in a diameter of 1200µm. The CA pattern

8 Channel 4 ns Digitizerrings in a diameter of 1200µm. The CA pattern (shown below) has 8 transmitting elements with total dimensions 310µm, in the imaging direction, by 1200µm wide.

8 Channel 4 ns Digitizer

Coded Aperture

transmission

pattern, 1200µm

2 GeV optics:

Coded Aperture

Fresnel Zone Plate

pattern, 1200µm

width

4 GeV optics:

Coded

Aperture

vertically

limiting slit

The detector is a vertical array of 32 InGaAsThree optical elements are available for 2GeV stored beam operation: a vertically limiting slit, a Fresnel Zone Plate (FZP), and a Coded Aperture

Aperture

4 ns XBSM Electronics ArchitectureFresnel Zone Plate

To match the characteristics of the ILC damping ring design, CesrTA is being upgraded to operate with 4ns bunch spacing. The new readout system for the xBSM provides 32 parallel 250MHz digitizers. Variable gain amplifiers have a range of

diodes with pitch 50µm and horizontal width 400µm. The InGaAs layer is 3.5 µm thick, which absorbs 73% of photons at 2.5keV; there is a 160nm Si3N4 passivation layer. The time

vertically limiting slit, a Fresnel Zone Plate (FZP), and a Coded Aperture (CA). These elements reside in the storage ring vacuum and can be selected and aligned remotely to meet the requirements of various measurements. At 2GeV, the typical power load on the optical element is of order 1 mW/mA; the optical elements are in contact with actively

LEPP, the Cornell University Laboratory for Elementary-Particle Physics, has joined with CHESS to become the Cornell Laboratory for Accelerator-based Sciences and Education (CLASSE).

250MHz digitizers. Variable gain amplifiers have a range of 24dB.

3 4

response of the detector is sub-nanosecond.of order 1 mW/mA; the optical elements are in contact with actively cooled copper supports to remove this heat.

LEPP, the Cornell University Laboratory for Elementary-Particle Physics, has joined with CHESS to become the Cornell Laboratory for Accelerator-based Sciences and Education (CLASSE).LEPP's primary source of support is the National Science Foundation. Visit us on the web at: www.lepp.cornell.edu