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--- group_10 [2018/09/13 15:31]
dombos
+++ group_10 [2018/09/14 09:19] (current)
seymour
@@ Line 91: / Line 91: @@
 After converging, the fitted value of Q2 is 0.1778619910379541. The original value of Q2 was 0.1828815622086947 (from section ''{Field for the standard particle ... scaled by QF to adapt field to right p/q}'').
 This is a (0.1828815622086947 - 0.1778619910379541) / (0.1828815622086947) * 100 = 2.74% decrease. This almost compensates for the 3% increase in the effective field length.
+**Problem 8**
+As stated in Problem 7, the mass resolutions of ''stgeorge.fox'' without any modifications are
+Mres_x = 60.123, and
+Mres_y = 59.262.
+We adjusted beam parameters until we saw Mres_x and Mres_y drop to around 55.
+The beam position (offsetting the optical axis) can be changed with the ''SA'' command.
+With ''SA 0.0005 0.0;'', Mres_x = 55.18793673041390 and Mres_y = 54.57598045160019. This is close to a 5% decrease.
+With ''SA 0.0 0.0014;'', Mres_x = 55.03721889327960 and Mres_y = 54.24635345218690. This is close to a 5% decrease.
+The beam size can be changed by adjusting the first and fourth parameter of the ''SB'' command to change the x- and y-extent respectively.
+With these two parameters each changed from the default 0.0015 to 0.0017, Mres_x and Mres_y each drop to about 55. A 0.2mm increase in size measurably drops the mass resolution.
+Decreasing these parameters only increases the mass resolution. It seems the smaller the beam spot, the larger the mass resolution.
+b) Adjusting the pitch, roll, yaw, x-position, and y-position of Q2 caused a drop in mass resolution at the mass slits (FP2), right after the Wien filter.  In COSY, "TA" is used to adjust the pitch and yaw, "RA" to adjust the roll, and "SA" to adjust x and y position.  Since the shifts are made relative to the central ray, they must be "undone" directly after the quadruple to prevent the shift form effecting the downstream elements.  The below plots show the relative effects on M_res.  For Q2 the mass resolution is more sensitive to changes in pitch and x-offset.
+{{ :angular_shifts.png |}}
+{{ :position_shifts.png |}}

JINA-CEE ION OPTICS SUMMER SCHOOL: JIOSS 2018

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