You can find Jixie's slices here: <a href="http://www.jlab.org/~jixie/talks/SeptumField.pdf">http://www.jlab.org/~jixie/talks/SeptumField.pdf</a><br><br><div class="gmail_quote">On Mon, May 2, 2011 at 11:17 AM, Jixie Zhang <<a href="mailto:jixie@jlab.org">jixie@jlab.org</a>> wrote:<br>
<blockquote class="gmail_quote">Minutes:<br>
<br>
1) Jixie showed some slices to introduce the information and status of the septum:<br>
A) The filed map: Bx vs. X|Z and By vs. X|Z, which shows that the current in the Tosca is opposite to the real <br>
B) Currently the septum center is located at z=686.46 mm, which is proved to be wrong. <br>
From Jixie's Geant4 simulation, it should be 772.40 mm, which is about 8.6 cm more downstream. <br>
John's prediction also suggested some position down stream.<br>
C)Confirm by Al that the septum can not be moved at all due to the fact that there is no space down stream. <br>
D) With current design, target located at -876.93 mm and septum at 686.46,<br>
the prediction bending angle by theory is 5.56 degree (some offset value of the septum itself not taken into account).<br>
E) Jixie's G4 simulation shows that the bending angle is 5.66 degree, using the septum map corresponding to <br>
3400 MeV electron. But we knew that the septum can not reach such a high current. <br>
F) Based on 2 map Robin provided, one for 400 MeV another one for 3400 MeV, Jixie scale the 400 MeV one by 8.5 then<br>
compare it with the other. There is about 0.2 Tesla difference in the field. which shows that in the 3400 map, the iron<br>
of the septum is saturated. John mentioned that the number 400 and 3400 itself could have large uncertainty due to<br>
the fact that these numbers is from a BdL accumulated along a straight
line in the Tosca model, not the real trajectory <br>of an electron. But
the conclusion that in high field of 3400 MeV, the iron is saturated
holds. Robin's "B vs I" plot also proves this.<br>
G) Robin provides the field map with the maximum current. The vertical range covers up to +/- 25 cm (requested by Jixie), <br>the real opening is a rectangle with vertical cover +/-12 cm only. <br>
<br>
2) The septum was found by Howard and John that there is one coil wired wrongly. Jixie will schedule with Howard to<br>
make a cross check for each coil to make sure all coils are wired properly. <br>
<br>
3) Al need to redesign the beam dump opening<br>
<br>
4) Al need to change the design of the sieve slits.<br>
<br>
5) Robin will try more efforts to check the maximum current of the septum and provide a new map. <br>
<br>
6) Once have the new map, Jixie will finalize the effect angle with Geant4 then finalize the beam dump opening, <br>also provide some fitting to Karl to calculate the kinematics and rates<br><font color="#888888">
<br clear="all"><br>-- <br>Best Regards,<br>Jixie Zhang<br>Jefferson Lab - Hall A - A112,<br><a href="tel:757-269-5352">757-269-5352</a> <br>_______________________________________________<br>
</font></blockquote></div><br><br clear="all"><br>-- <br>Best Regards,<br>Jixie Zhang<br>Jefferson Lab - Hall A - A112,<br>757-269-5352 <br>_______________________________________________<br>