Progress Report of Region3
On Monday the Linux
hard drive containing my Geant4 simulation code (including a
Geant4->OpenCascade->CAD file converter) just died
completely without any warnings.
The Windows
drive is partially damaged (head crash ?), could not recover the
partition with my home directory containing my SolidWorks drawings
(Murphy's Law ....)
My backup is ~3
weeks old, fine for my Geant4 code but I have to update my drawings
from temporary printouts rescued from the trash can ....
1) VDC design
Getting quotes for G10/G11 and 4411W (Stesalit) sheets (size: 48"x96",
Thickness 0.5" and 0.625"). Since G10 and 4411W are laminates
(pressed and rolled), the surfaces are under tension.
Any surface machining will release this tension resulting in twist and
bow of the sheet, which makes a precision machining quite difficult.
Out of 16 companies only 2 !!! are aware of this
problem and offer stress relieved sheets (Atlas-Fibre and Stesalit:
surfaces are grinded or sandblasted on both size), actually those
companies do precision machining on laminates as well and
can handle this extreme sheet size.
Just received two 4411W (product name: Stesalam EP107-M950-40) sample
sheets, each in the size of a postcard. I will pass them to JLab
machine shop in order to figure out how precise
this material can be machined (limited by chipping and flaking). The
most precise part of the VDC is the "bear on bridge" defining the
vertical position of the wire with a precision of 50um
and better. Still waiting for G10/G11 samples.
As I stated in the last report, for the Mainz VDCs/HDCs the
Pyralux sheets (~copper cladded Kapton) with an ashesive layer
were glued under pressure using heat pads at 175C for ~2h
on G10 and 4411W. Talking to various G10 companies about this
postprocessing they demurred that G10 can only sustain up to
~155C without damage (same for 4411W: ~160C).
HERMES improved the quality of gluing Pyralux sheets on a carrier
using a prepreg (adhesive sheet) epoxy curing at ~150C. Before they
used a regular but messy epoxy glue technique
which was discarded, see elog
. We have to avoid residual gas channels between the Pyralux and the
frame dodging the gas sealing.
The epoxy TF D-18-1F is approved for low outgassing and cures at
150C.
The gluing will be accomplished using a rectangular "flat iron"
with a thin teflon surface area (does not stick to the glue) kept at
150C. This will be archived by attaching flexible heater elements
(Kapton or Silicon based) on a plate (alu or steel).
Pic below: several flexible heater elemets assembled for obtaining a
hot plate with uniform temperature
2) Wire Scanner
The wire scanner translation stage has arrived. It has a travel range
of 48 inch and is equipped with a linear position sensor (glass rulers)
with a resolution of 8um or even 2um, depending on the readout.
We just hooked up the stepper motor + controller for first tests and
Joe is currently setting up the controller (home position, end
switches, etc)
.
3) Online Documention of QweakSimG4
Just started to use doxygen
for a online documention of the source code. The result is a web based
documentation, a very first version can be seen see here.
It is far from beeing complete, but at some point you have to start
documentation. The documentation is added as special comments within
the source code, so it is quite
easy to implement, see example below:
00086 TopoDS_Shape Torus(double Rmin, double Rmax, double Rtor, double SPhi,
00087 double DPhi);
00088
00089
00090
00091
00092
00093
00094
00095
00096
4) Electronics: I2C
interface
Graduate student Pjerin Luli and I have finalized the design for a PCB
layout for an PC->Frontend Electronics adapter card, which will
be connected to the printer port (25 pin D-Sub).
At present we almost have completed a
mockup receiver board with the same I2C I/O controller/expander
(Philips PCF
8574) to be used for switching on/off individual
MAD channels indicated by LED's.
Pic below: Screenshot of EAGLE layout program (Student
version). The schematics of the PC->I2C adapter is shown on the feft
, the derived board layout is shown on the right
Pic below: The schematics of the I2C receiver is shown on the
feft , the derived board layout is shown on the right
That's all folks !