|
10 June 2003 |
Location |
Phone Number |
Access Code |
|
WH-2 NE |
865-673-6703 |
334823 |
Progress Updates and Issues
- Upstream Beamline
- Targets
- TPC - Time Projection Chamber
- Magnets
- CKOV - Cerenkov
- DC - Chambers
- TOF - Time of Flight
- RICH - Ring Imaging Cerenkov
- ECAL - EM Calorimeter
- NCAL - Hadron Calorimeter
- Gas Systems
- DAQ - Data Acquisition
- MC - Monte Carlo
- Installation
- MC7 - Enclosure and Counting House
- Meetings
- Project Management
Leon Beverly's meeting summaries in italics.
BEAM - Beamline
UBL - Upstream Beamline Detectors
BCKOV
TGTW - Target Wheel
Jerry Peterson:
The target wheel is suspended from four stainless rods. These slide through bronze bushings at the upstream support, at the vertical optical bench. There are solid locks to make sure that the JGG fringe field does not draw the wheel in beyond its desired position.
At its most downstream, the downstream face of the wheel sits about 1/4" from the TPC window. If thick targets are used, sticking out from that face, we will need to slide the system upstream to avoid contact with the window.
The upstream flange, protruding supports etc. stick a few inches upstream of the optical bench. We will need some room to undo this to move the target upstream, and the rods will stick another 13" or so upstream at full retraction. If stuff upstream is too close, we would have to remove the optical bench to install and make big moves.
Does LLNL have a suitable piece of gold to make a target? I have not yet invested in this. We need a 2" diameter disk, 1 mm thick, mass about 38 gm.
It is an RS232 connection that drives the system. I am running the wheel now from a PC, and debating the utility of the local hand controller. The system is really slick, with the ability to enter the names of the targets into the program, to lessen the chances of error in the middle of the night.
If anyone wants deuterium at an early stage, please tell me now, so that I can machine one of the spare wheels to take my 3" diameter CD2 samples. I have three wheels.
Peter Barnes:
The "IN" position sounds perfect. Will we mount the targets flush with the downstream face of the wheel? The upstream protruding supports in both the "IN" and "OUT" positions won't be a problem. Access to move the wheel in and out won't be a problem. I've forgotten the answer to the question of how we change target wheels - through the port of from the side? I'll look in to the gold target. We have provision for RS232 connections fed back to the counting house computers (tunneled through the net, actually - works transparently).
Jerry Peterson:
Some of the less dense targets, even at 1%, stick a bit downstream from the face of the wheel. Someone is bound to be in a hurry, so I have some 2% targets that stick several mm downstream. Life would be simplest if we settle on one and only one position, but the rods slide to allow this, and we can set a lock screw for long term stability. The physically thin targets can be put on top of spacers to keep the center of each target at some fixed position for fixed solid angle.
We would change wheels by sliding the rods upstream to allow an arm to reach in from the side. There is one upstream screw to hold the wheel to its mechanism, and we would place the wheel from the downstream side. I plan not to have the cover plate on the wheel, for less material in the general area and to allow for thicker targets. This means we need to keep the box clean, to keep dust and crud out of the works.
I plan to test the system in a B field this week.
Peter Barnes:
Ron Soltz pointed out to me that we will have to run the acceptance calculation for each target in any case, so there is no saving in effort to align the target centers. Instead, our priorities should be a) do what is technically easy, b) maximize the acceptance from each target individually by mounting each as downstream as possible.
CTGT - Cryogenic Targets
NTGT - NuMI (MINOS) Target
Peter Barnes:
Sten pointed out that the JGG fringe field at the position of the TPC DC power racks might be bad for the transformers. Do we have any data (or model?) out there? Maybe some kind of map to decide how far away to keep the racks?
Holger Meyer:
What field can the DC towers work in? I can look up numbers from the fieldmap. We have data upstream of the JGG, but restricted to the aperture of the magnet in x and y. From this we can make good guesses for the field at the rack positions.
Peter Barnes:
Don't know the limit field for sure. Can you make a plot of the field magnitude along the Y-Z plane at the edge of your sampling volume? That should be an upper limit on the field outside that volume, as long as we stay away from the steel.
ZipTrack
JGG - Jolly Green Giant
Rosie
DC1-4 (E690 Chambers)
DC5 & DC6 (Iowa Chambers)
Alignment
The next call will be Tuesday, 17 June 2003, at 1:00 PM CDT in WH-2NE, Snake Pit.