# Presentation: 769972

## Beam Measurements and Upgrade at BL 7.2,the Second Diagnostics Beamlineof the Advanced Light Source

**PAC 2005**
**Knoxville, TN**

- May 17, 2005

**Tom Scarvie**
**ALS Accelerator Physics**

## Contents

**PAC 2005**
**Knoxville, TN**

- May 17, 2005

**Contents**

** ****Overview of diagnostic BL 7.2 **
** ****Combined measurements with diagnostic BL 3.1**
** ****Momentum spread**
** ****Emittance**
** ****Visible and IR port**
** ****Streak Camera Measurements**
** ****Coherent Synchrotron Radiation bursting**
** ****Resolution problem and effect**
** ****Future plans and summary**

## A Team Effort

**PAC 2005**
**Knoxville, TN**

- May 17, 2005

**A Team Effort**

**Accelerator Physics:**** Fernando Sannibale,**
**                                     ****the entire ALS Physics Group**

**Mechanical Engineering:**** Dennis Baum**
**	****	****	****	****Nicolas Kelez**

**Control System & Software:**** Alan Biocca,**
**	****	****	****Toshiro Nishimura, Eric Williams **

**IR & Visible Optics:**** Mike Martin**

**Many Thanks to Karsten Holldack (BESSY) !**

## BL 7.2  Plan View

**PAC 2005**
**Knoxville, TN**

- May 17, 2005

**BL 7.2  Plan View**

**The entire beamline is inside the ALS shielding walls**

## BL 7.2  3-D View

**PAC 2005**
**Knoxville, TN**

- May 17, 2005

**BL 7.2  3-D View**

- Viewing Assembly at 8 m

- Pinhole & X-ray BPM at 6m

- Filter Attenuator

- Pinhole

- Visible Mirror

## BL 7.2  Actual Views

**PAC 2005**
**Knoxville, TN**

- May 17, 2005

**BL 7.2  Actual Views**

## BL 7.2 Pinhole System Scheme

**PAC 2005**
**Knoxville, TN**

- May 17, 2005

**BL 7.2 Pinhole System Scheme**

| R1 [m] | 6.08 |
| --- | --- |
| R2 [m] | 2.04 |
| Photon Energy [keV] | 16.33 |
|  [Ang] | 0.76 |
| Pinhole Diameter [m] | 20 |
| System Resolution [m] | 22 |

**Filter: Molybdenum**
***E***** = 16.33 keV  *****E/************E***** = 2.3 (FWHM)**

## What is the benefit of a pinhole array?

**PAC 2005**
**Knoxville, TN**

- May 17, 2005

**What is the benefit of a pinhole array?**

**Phosphor Screen**

**Peaks’ Gaussian FIT**
**Emission Angle & Position**
**and Opening Angle**

**Main advantage of pinhole array is insensitivity to alignment**

## X-ray  BPM 

**PAC 2005**
**Knoxville, TN**

- May 17, 2005

**X-ray  BPM **

********  ****is a function**
**of beam position**

**Secondary emission**
**induced by **
**synchrotron radiation **

**Two pairs of Cu Blades**
**BESSY II Scheme**

## X-ray BPM and pinhole assembly

**PAC 2005**
**Knoxville, TN**

- May 17, 2005

**X-ray BPM and pinhole assembly**

## Visible & Infrared Port

**PAC 2005**
**Knoxville, TN**

- May 17, 2005

**Visible & Infrared Port**

**Longitudinal bunch distribution measurements**
**using visible synchrotron radiation (streak camera, photon counting, ...)**

**Infrared and Far-Infrared**
**synchrotron radiation measurements**

## Viewing System Assembly

**PAC 2005**
**Knoxville, TN**

- May 17, 2005

**Vie****w****ing System Asse****mbly**

**7****:****1 Zoom and Focus**
**remotely controllable**

## Data Analysis System

**PAC 2005**
**Knoxville, TN**

- May 17, 2005

**Data Analysis System**

**Very positive results, so the**
** ****same system is being exported to BL 3.1**

**The analysis Software, developed in**
**C++ on a Linux platform,**
**runs continuously at ~ 10 Hz,**
**calculating quantities and updating**
**EPICS process variables (PV)**

**A GUI window reads the PVs**
**and presents and visualizes the data**

## Beam Size Measurement Example

**PAC 2005**
**Knoxville, TN**

- May 17, 2005

**Beam Size Measurement Example**

## Overall Status of BL 7.2

**PAC 2005**
**Knoxville, TN**

- May 17, 2005

**Overall Status of BL 7.2**

**Low background**
**High photon flux**
**Complete system is working well**
**Attenuation had been characterized and agrees with specifications**
**Linearity is good**
**Resolution is slightly out of specification**
**Not a major detriment to our measurements**
**X-ray BPM commissioning coming soon**

## Pinhole System Main Goal

**PAC 2005**
**Knoxville, TN**

- May 17, 2005

**Pinhole System Main Goal**

**Combine horizontal profile measurements from BL 7.2**
**and from the existing diagnostic beamline BL 3.1 **

## Differences between BL 7.2 and BL 3.1

**PAC 2005**
**Knoxville, TN**

- May 17, 2005

**Differences between BL 7.2 and BL 3.1**

- Source in the central dipole of the ALS Triple Bend Achromat

| BL 7.2
Source Point | Value |
| --- | --- |
| x [m]  | 0.9 |
| x [m]  | 0.07 |
| xrms [m]  | 105 |
| R  | 1.24 |

| BL 3.1      Source Point | Value |
| --- | --- |
| x [m]  | 0.35 |
| x [m]  | 0.03 |
| xrms [m]  | 57.1 |
| R  | 2.63 |

- Source in the first dipole of the ALS Triple Bend Achromat

**Ratio between Emittance and Momentum Spread Contributions to Beam Size**

## Momentum Spread andEmittance Measurement

**PAC 2005**
**Knoxville, TN**

- May 17, 2005

**Momentum Spread and****Emittance Measurement**

## Streak Camera Measurements

**PAC 2005**
**Knoxville, TN**

- May 17, 2005

**Streak Camera Measurements**

**ALS longitudinal bunch distributions are now**
**measured using a streak camera at BL7.2.**
**Eventually we will use bunch length vs. current scans to get an independent measurement of the microwave threshold.**

## CSR Bursting Measurement

**PAC 2005**
**Knoxville, TN**

- May 17, 2005

**CSR Bursting Measurement**

**Coherent synchrotron radiation measured through**
**the visible & infrared light port at BL 7.2**

## BL 7.2 Resolution Measurement

**PAC 2005**
**Knoxville, TN**

- May 17, 2005

**BL 7.2 Resolution Measurement**

**Design: 24.2 mm      ****Measured: 33.4 ********m**

**Measurements (********m):**
**25.1  27.8  23.1  31.1  24.5**

**Measured 5 different holes, randomly selected, on a tungsten pinhole spare.**

**The nominal pinhole diameter is 20 microns.**

## Resolution Not Quite to Spec

**PAC 2005**
**Knoxville, TN**

- May 17, 2005

**Resolution Not Quite to Spec**

**The momentum spread-emittance measurement error depends weakly on resolution**

**In the ALS configuration the resolution is dominated by the geometry of the pinhole...**
**the dependence on the photon energy is weaker**

## Summary

**PAC 2005**
**Knoxville, TN**

- May 17, 2005

**Summary**

** ****Successful commissioning of BL 7.2**
** ****Very good mechanical engineering and installation**
** ****Control and data analysis systems work well**
** ****Visible and IR light port are great for longitudinal beam  **
**        ****measurements and CSR studies**
** ****Resolution larger than expected**
** ****Pinhole array does not meet specification**
** ****Will install better array soon**
** ****Will duplicate the BL 7.2 imaging system at BL 3.1**
** ****Commissioning of X-ray BPM is the last step**

## Thanks for Listening!

**PAC 2005**
**Knoxville, TN**

- May 17, 2005

**Thanks for Listening!**