Changes

A light-sealed enclosure for the Tagger Microscope is under design. The following requirements have been set forth to constrain it:

A light-sealed enclosure for the Tagger Microscope is under design. The following requirements have been set forth to constrain it:

== Managing 500 Fibers ==

== Managing 500 Fibers ==

In an effort to manage this large two-dimensional array of 5x100 fiber pairs (scintillator and its waveguide), it has been segmented into 20 fiber modules, 5x5 each. This is a convenient unit both mechanically and in terms of readout: on the electronics end the DAC supplying bias voltages to individual SiPMs have 32 channels and consequently, the SiPM bias and amplifier board has been instrumented with 32 SiPMs. Each fiber module with its 25 fibers is nicely paired with one board (leaving 7 spare channels). This arrangement also makes channel addressing very convenient.

In an effort to manage this large two-dimensional array of 5x100 fiber pairs (scintillator and its waveguide), it has been segmented into 20 fiber modules, 5x5 each. This is a convenient unit both mechanically and in terms of readout: on the electronics end the DAC supplying bias voltages to individual SiPMs have 32 channels and consequently, the SiPM bias and amplifier board has been instrumented with 30 SiPMs. (The two remaining channels have been reserved for DAC calibration and SiPM amplifier gain control.) Each fiber module with its 25 fibers is nicely paired with one board (leaving 5 spare channels). This arrangement also makes channel addressing very convenient. A 5x6 bundling with 17 resulting modules is another approach, and will likely be adopted if the spare channels per electronics set is not thought necessary.

The bundle of 25 fibers is glued together and then glued onto an aluminum strip with alignment bolts on both sides. The strips allow precise mounting and fastening onto a set of rails (described below). The current assembly plan requires each the modules to be inserted sequentially from one side along these rails in the positioned forced by the rail configuration. In most cases (when aligning to small crossing angles) the modules will be parallel to one another and may be aligned against each other.  

The bundle of 25 fibers is glued together and then glued onto an aluminum strip with alignment bolts on both sides. The strips allow precise mounting and fastening onto a set of rails (described below). The current assembly plan requires each the modules to be inserted sequentially from one side along these rails in the positioned forced by the rail configuration. In most cases (when aligning to small crossing angles) the modules will be parallel to one another and may be aligned against each other.  

The 83 oz⋅in Lin Engineering 4118L-01 (1.9") Step Motor has been chosen. The unit is close in price to the lower torque models and does not exceed the 2 A limit of the inexpensive [[:media:StepMotorDriver_R208-manual.pdf|driver]] (meant for lower-end motors).  

The 83 oz⋅in Lin Engineering 4118L-01 (1.9") Step Motor has been chosen. The unit is close in price to the lower torque models and does not exceed the 2 A limit of the inexpensive [[:media:StepMotorDriver_R208-manual.pdf|driver]] (meant for lower-end motors).  

The combination of these devices have been found easy to control: the driver has simple direction and step resolution selection pins and uses TTL pulses as step commands. The shaft of the motor, which comes smooth (as in the adjacent picture) when bought from distributors. However, it tested to be more than soft enough to machine a flat into it. A cylindrical "sleeve" with threaded outer surface may be inserted over it and tightened against the flat a small headless screw.

The combination of these devices have been found easy to control: the driver has simple direction and step resolution selection pins and uses TTL pulses as step commands. The shaft of the motor, which comes smooth (as in the adjacent picture) when bought from distributors. However, it tested to be more than soft enough to machine a flat into it. A cylindrical "sleeve" with threaded outer surface may be inserted over it and tightened against the flat by with set screws.

 

== Adjustment to the Electron Crossing Angle ==

== Adjustment to the Electron Crossing Angle ==

{|

{|

| [[Image:CrossingAngle_lowE.png]] || [[Image:CrossingAngle.png]]

| [[Image:CrossingAngle_lowE.png|350px]] || [[Image:CrossingAngle.png|350px]]

|-

|-

|  [[Image:ParallelRailingConcept.png|370px]]

|  [[Image:ParallelRailingConcept.png|370px]]