310212_IOTA_Proton_Injector_BPM_Specification.pdf

IOTA Proton Injector BPM Specification, dated 7/27/2020

The IOTA Proton Injector at the FAST facility requires a Beam Position Monitor (BPM) system including five (5) bpm assemblies, any required intermediate electronics, and a front end capable of providing readbacks to the Fermilab accelerator controls network conforming to the following specifications.

-- Beam Conditions --

Pulsed beam operation at 1 Hz.

Bunched beam at 325 MHz.

Bunch length, 50 mm to 200 mm.

Pulse length range, 0.1 μs to 100 μs.

Beam Current range, 0.1 mA to 20 mA.

This is a range of 10 pC/pulse to 2 μC/pulse

-- Geometry --

2.15 in (54.61 mm) in diameter beam-pipe.

Pickups must not occlude 50 mm diameter.

Quadrupole Magnet Coil Length, 6.22 in (158 mm).

-- BPM Performance --

Position Measurement accuracy, <250 μm.

Position Measurement resolution, <100 μm.

Measurement Range (w.r.t. beam-pipe), >50%

Electronics Response time, <0.20 ns (50 MHz)

External Beam Pulse Trigger, I.e. gated ADC data acquisition.

-- BPM Frontend / Data Interface --

While bunch-by-bunch is not necessary, we would like to track progression of the beam pulse through the length of the pulse in < 0.1 us resolution (thirty-three 325 MHz bunches averaged or better). Data should be gathered using digitizers and formatted into arrays by a coordinating front end that can be accessed via ethernet connection, preferably using an embedded EPICS 7 IOC, MODBUS, or generic

TCP/IP serial protocol (negotiable).

These data arrays should include the following (7 arrays per BPM assembly):

Raw digitizer counts for each channel (four channels per BPM assembly)

Horizontal and Vertical positions (scaled opposing channel subtraction)

Intensity (channel sum)

Any controllable parameters and readbacks should be accessible through the same mechanism as data array readout. These should include at least any internal attenuation, software offsets, and saturation indications. The frontend itself will be placed outside of the accelerator enclosure, and any cabling will be addressed separately.