Customer Solutions

Particle Detector Testing Controlled by LabVIEW Datalogging and Supervisory Control Module

Author(s):

Christian Dechlette, CERN

Industry:

Energy/Power

Product:

GPIB & Instrument Control, LabVIEW, Serial

The Challenge:

Creating a simple, easy-to-use program to control and test a muons chamber with enough precision to work effectively in a large proton collider

The Solution:

Using National Instruments software and hardware to create a scalable solution

Introduction
CERN is one of the world’s largest scientific physics laboratories. In our large proton collider (LHC, 27 km), we installed detectors at various points. To detect the trajectory of the MUONS, an atomic particle, we used the drifts (1,200) made in several laboratories. These MUONS rooms consist of tungsten wire 50 µm thick placed inside an aluminum tube 30 mm in diameter and 0.4 mm thick. The tomograph, which defines the position of wire in the room and the distance between two wires with a precision of 5 µm, uses two narrow x-ray beams that successively light sections of the room while two scintillators record the profile of absorption. We record all the data in a VME interface and a PC running BridgeVIEW.

We use BridgeVIEW to supervise the ordering of the displacement of X sources, and the data acquired by the VME interface. Simultaneously, the experiment controls the tomograph environment, manages the feedings for X sources, and maintains access control in the clean room.

Our Goal
Our goal was to use a tomograph as a quality control tool to measure and control the position of wires in the MUONS chamber room and the distance between two wires with a precision of 5 µm.
To measure the distance between two wires, we placed two X-ray sources on a mobile chariot. These sources emit photons collected by scintillators through absorption as the photons pass through the room so we can determine the location of the wires. To accomplish this, we divided the architecture into two parts - acquisition and control equipment.

Acquisition
Data was collected using a VME system. We wrote the program using C for an OS9 CPU system. We gathered the data on a PC through a VME-MXI-2 interface. There are two measurements - passive and active. The active measurement is the same as the passive one, with the exception that the gas (CO 2 ) in the tubes and a HT voltage (4 kV) go through the wires. We monitored room temperatures with a National Instruments CAN interface.

Control Equipment
A Pentium PC with Windows NT manages the entire system. To communicate we used RS-232, PROFIBUS, VME-MXI-2, and CAN. We decided to use BridgeVIEW to take advantage of built-in tool such as historical logging, security, networking, and alarming, specifically designed for control applications.

Conclusion
National Instruments products helped us realize this experiment and test these chambers for use in the LHC ring. We chose the National Instruments BridgeVIEW graphical SCADA development environment to create user-friendly graphical user interfaces (GUIs) because of its flexibility and the built-in tools to implement historical logging, security, networking, and alarming. We designed the GUI so that anyone from any technical background could manipulate and use it.
The solution we developed was only one user interface so that we could group all the I/O from different interfaces. We took our first steps with LabVIEW and easily ported the code to BridgeVIEW without any reprogramming.

For more information, contact:

Christian Déchelette

Engineer

CERN

Rte de Meyrin, Geneva

Tel: 022 767 6373

E-mail: christian.dechelette@cern.ch

efttzk.pdf

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