Online Spin Flip

This main page of Spin Flip Control System for Hall A He3 Polarized Target.

Some Quick Links:

• Shift Worker Quick Start
• Experiment Transversity
• Target Index Page

Introduction

Spin Flip System is designed for controlling Hall A Polarized He3 Target automatically flip spin direction during experiment run time. The physics goal is to reduce systematic false asymmetry, driven by experiment Transversity and d2n.

Core functions for this system are

1. Control the target spin flip consequence
2. Acquire and Record target spin state
3. Output target spin related information into DAQ system, therefore data stream
4. Interaction with human (Target Operator)
5. Communicate with related target software/hardware

Physics of Spin Flip

Please refer to Thesis of Xiaochao Zhen, Charpter 4 Polarized He3 Target

System Structure

Spin Flip System Diagram

Exception Handling

Exception Handling for spin flip system will be discussed as following.

Preventing an error from happening

It's important to pay attention to warning messages and yellow colored controls. They usually indicates a potential source error. Understanding the source would save some further trouble.

Shift worker HOWTO of Exception Handling

When the system detect an exception, an error will be raised. Then:

• System status indicator on main control window and system status manager will show an ERROR state and flash.
• An alarm will sound trough speaker. The alarm could temporarily silenced from system status manager.
• Automatic Spin flip will be suspended.

To recover to normal state, one should:

1. click Clear Error button on system status manager to acknowledge the alarm
2. identify and resolve the source of error
3. recover the automatic spin flip

Exception Analysis

There are several types of resource for experts to analysis an exception during run time or after

Text Log File

Text Log is a useful resource to trace system history. It's organized in the Message Handler window as well as recorded into a text file (also specified on Message Handler window). Basically, every step the system took, every warning and error message are recorded.

Status Page

Status Page Contain two list of status reports of target control software. They are User Report and Automatic Report.

• User Report are generated by pressing "generate report" button on target Main Control GUI. It includes following sections:
  • User Comment (If there is any)
  • System Status variable list
  • Screen Shots
  • NMR Signal History
  • a copy of text Log File
• Automatic Report are automatically generated after every spin flip or once an error occurred. It's a simplified version of user reports.