12-BB-BPM BaseBand BPM Electronics - 李子佳-粒子加速器束流测量诊断

BaseBand BPM Electronics

Non-intercepting beam position measurement

For cancer therapy synchrotrons

Tracks the beam during energy ramp

Beam intensity range

> 70 dB

Operating frequency

Up to 25 MHz

Principle

Based on the pioneering work of Robert E. Shafer at Los Alamos Laboratory,
the Log-Ratio BPM derives beam position from logarithm of the ratio of opposite pickup signals: Log(A/B).
Position measured by this method is more linear, over a wider range, than difference-over-sum.

Front-end Filter and Amplifier BB-BPM-FEFA

Four BB-BPM-FEFA are required for each BB-BPM plug-in module, one per pickup.
BB-BPM-FEFA has been specifically developed to measure low intensity ion beams.
It is best to install it very close to the stripline or shoebox pickups to minimize capacitive loading.
Control of BB-BPM-FEFA gain is done by FO fiber optics, one per front-end amplifier.
FO high level switch the gain from 0dB to nominal value.
A single control FO can be daisy-chained to all front-end amplifiers.
The FO signal is under user's control.

Features

The BaseBand BPM is a log amplifier-based beam position monitor. It operates up to 25MHz.

Output signals are analog voltages:

X&Y narrowband outputs for close orbit measurement
X&Y wideband outputs for machine study, to see orbit changes or instabilities during the ramp

Cable length matching not required: pickup signals don’t need to be in phase

To prevent noise pickup by way of ground loops:

The front-end amplifiers and filters are powered via their RF output coaxial cables
The front-end amplifiers gain is controlled by fiber optic signals

Specifications

Beam intensity range

Frequency range

Input signal

Input noise

>70dB

200kHz - ≤25MHz

BB-BPM-FEFA: High impedance, 2.5Vmax

BB-BPM: -70dBm…+5dBm

BB-BPM-FEFA: 25nV/√Hz

BB-BPM: <-70dBm

Datasheet