A1900 Hardware and Detectors

This page provides a brief introduction to what hardware and detectors are located where in the A1900. A more detailed list providing the most up-to-date description of the standard A1900 detector and hardware configuration can be found in the A1900 Service Level Description (PDF).

All detectors, viewers, targets, slits, and wedge degraders used with the A1900 can be remotely inserted into the beam and removed. The items which are inserted at the time a Barney saveset is made are documented in the saveset.

The vacuum chamber at the A1900 target position contains 4 ladder drives (named Z013TL, Z014TL, Z015TL, and Z016TL) each with up to 8 positions for holding things like targets, thin stripping foils, viewers, and apertures. A faraday cup for measuring beam current is located on Z014TL. Z015TL is at the A1900 object position; Z013TL and Z014TL are upstream of the object position, and Z016TL is downstream. A list of the commonly used targets and apertures is availible in the A1900 Service Level Description (PDF).

The vacuum chamber at Image 1 (I1) contains a remotely-adjustable set of horizontal slits. It also has a drive which can hold either a wedge or a blocker on the optic axis to stop a charge state of the primary beam.

The vacuum chamber at Image 2 (I2) contains a number of devices. A ladder drive holds up to two wedges and a viewer. A list of the commonly used wedges is availible in the A1900 Service Level Description (PDF). There are two drives for remotely inserting horizontal slits; adjustments to the gap size of these slits can only be made manually when the system is not under vacuum. There is a pair of parallel plane avalanche counter (PPAC) detectors for tracking the horizontal and vertical position of particles passing through them. There is also a thin scintillator detector which is used to provide timing start or stop signals for particles passing through it.

The vacuum chamber at Image 3 (I3) contains a remotely-adjustable set of horizontal and vertical slits. It also has a ladder drive which holds a viewer and one degrader.

The vacuum chamber at the focal plane (FP) contains most of the detectors typically used in the A1900. A pair of PPAC detectors is used in obtaining proper positioning for particles at the focal plane. Downstream from the PPACs is a remotely adjustable set of horizontal and vertical slits. A thin scintillator (called the XF scintillator) is available to provide a timing signal for particles that pass throught it. A thin silicon PIN detector measures the energy loss of the particles passing through it. A thick scintillator is used to measure the energy and arrival time of particles that it stops.