These notes summarize the changes needed in the input parameters to
PISA in order to make the mass of the MVD in the simulations agree
with the mass of the MVD in the real design. In the notes below the
"old" model refers to the PISA model used up until now, including
in the 10K run. The "new" model refers to the model I propose to start
using now -- which is much closer to the MVD design shown in the
MVD design book.
| part name in PISA | part name in design book | mass in old model (gm) | mass in new model (gm) | notes
| Motherboard
| Motherboard, | LDOs, connectors, cooling ... 1148
| 2692
| radius increased, | more detailed components enclosure | endcaps endplate | assembly 1898
| 2676
| radius increased
| electronics | (MCMs in barrel) MCMs | in barrel 402
| 1300
| they got thicker and | wider and the material was G10 not alumina bus cable
| power/comm | cable 166
| 1265
| changed from a | kapton cable to a circuit board enclosure
| inner/outer | cover 773
| 846
| radius increased
| struts
| struts
| 269
| 338
| OD increased from | 1 to 1.25 inch dummy MCMs
| dummy MCMs
| 0
| 271
| previously not | in simulations Si in barrel
| Si in barrel?
| 245
| 245
| no changes
| (cooling) plenum
| plenum
| 206
| 218
| MCMs got bigger
| Mounting | plate endplate | adapter 64
| 72
| about the same
| rohacell frame
| cage
| 82
| 63
| ribs thinner
| Si in pads
| Si in pads?
| 52
| 52
| no changes
| total MVD
| total MVD
| 5305 gm
| 10036 gm
| design book | says 10975 gm |
On April 30, 1998 a the mass of the "bus cable" a.k.a. "power/comm cable" was changed from 2433 gm total to 1265 gm total. This reflects a modification in the cable design which was made to reduce the mass. The parameter VER_TH_BUS_CABLE in phnx.par had to be changed from 0.25 to 0.13 to account for this design improvement. This change is reflected in the table below.
The only material I know I have omitted from the PISA code is the kapton cables from the Si to the MCM's (which I left out because PISA crashes when I put it in and I can't figure out why). These cables should have a total mass somewhere around 1/3 or so of the mass of the Si in the barrel (therefore around 245/3 = 82 gm).
I propose changing the following parameters, which are input to PISA (via the phnx.par file) to set up the new pisa code shown above:
| parameter name | old value | new value | notes
| R2_VER_ENC
| 23.165 cm
| 28.35 cm
| inner radius of MVD | outer (rohacell) cover DZ_VER_ENDPL
| 0.109 cm
| 0.10 cm
| half-thickness (dz/2) of
| enclosure endcap (aka enclosure endcap) DZ_VER_MOPL
| 0.048 cm
| 0.054 cm
| half-thickness (dz/2) of
| mounting plate (aka endplate adapter) DVOEL(1)
| 2.00 cm
| 2.15 cm
| dx/2 of MCM
| DVOEL(2)
| 0.055 cm
| 0.076 cm
| dy/2 of MCM
| DZ_VER_PMB
| 0.16 cm
| 0.21 cm
| half-thickness, motherboard
| R_VER_PMB
| 19.0 cm
| 25.0 cm
| outer radius, motherboard
| VER_EL_SPACE
| 0.8 cm
| 0.85 cm
| spacing between MCMs in plenum
| VER_TH_BUS_CABLE
| 0.043 cm
| 0.13 cm
| full thickness of | power/comm cable VER_W_BUS_CABLE
| 3.0 cm
| 7.5 cm
| full width of | power/comm cable WDVROH
| 0.6 cm
| 0.54 cm
| width of ribs in | rohacell cages MED_VER_BUS_CABLE
| 108 | = kapton 107 | = G10 material for | power/comm cable MED_VER_MCM
| 107 | = G10 103 | = alumina material for MCM
| MED_VER_DUMMY
| --
| 106 | = aluminum new definition of | material for dummy MCM |
In addition to these input parameter changes, I will have to make a few changes in the PISA code because the current code assumed the partially populated sectors of the MVD do not have power/communications cables going to them. However, the current "official" design assumes that all 24 power/comm cables are the same. Removing the unneeded sections would remove roughly 2/3 of the mass from 8 of the 24 power/comm cables, reducing the mass by around 281 gm (probably a little less than this). Adding the dummy aluminum (or other material) plates in the cooling plenum also requires some code changes. The files I need to change in pisa are summarized below:
| file name | description of change
| pisa/src/ver/ver_pars.f
| Add new parameter MED_VER_DUMMY_MCM (tracking | medium) for "dummy MCMs", add default value for MED_VER_MCM, change default values for changed parameters (i.e. the parameters in the table above) pisa/src/ver/ver_plen.f
| added "dummy MCMs", all "bus cables" aka | "power/communications cables" are now the same size, previously there was a smaller type corresponding to sections of the detector with incomplete Si coverage pisa/bin/phnx.par
| changed values of the parameters in the table above, | added new parameter MED_VER_DUMMY_MCM pisa/inc/fpvlink.inc
| add new parameter OFVA_MED_DUMMY, used as a | pointer in, the MVD geometry parameters bank pisa/inc/gugeom.inc
| increase radial boundary of MVD from 25 to 30 cm
| |
Here is a little history the total MVD mass in PISA:
| date | total MVD mass in PISA (gm) | notes
| 23-Aug-94
| 7855
| endplates were made thinner | after this, outer radius 20 cm 16-Apr-97
| 5324
| outer radius 25cm
| 4-Feb-98
| 11207
| outer radius 30 cm
| 30-Apr-98
| 10954
| Power/Comm cable mass reduced
| |