Chapter 5: Inflight Performance

  

5,2 Cover Close Calibrations

 

5,2.3 PHA Analysis

 

This section describes an analysis that was undertaken in IDL to better understand the SEEPHA matrix. Figure 5.18 shows a 3D plot of the matrix shown in Figure 5.9 made with the IDL routine shade_surf. The tallest peak corresponds to the Cm source. The peak corresponding to the Gd source is to the left of the Cm peak and towards the top of the figure. The large number of scattered He which are counted as H because of the priority scheme can be seen in the elongated peak in front of the Gd peak and in the peak to the right of the Cm peak.

 

Figure 5.18 PHA matrix for 92049 calibration

 

 

 

Figure 5.19 PHA matrix for 92049 calibration

 

 

The matrix was divided into five areas as shown in Figure 5.19, and PHA matrix for 92049 calibration. Summations were made over each section to determine the number of counts in each region. It is difficult to draw many conclusions because of the distortions created by the priority scheme. However, one can compare the percentages in each area from one calibration to the next to verify that they don't change very much. This is done in Table 5.14.

 

Table 5.14 PHA counts/percentages

 

Date/Time	CM peak	Gd Peak	Area A	Area B	Area C
93019.20-22	3193/36.1	1375/15.6	3488/39.4	597/6.8	172/1.9
92009.22-24	2079/39.2	917/17.3	1875/35.3	386/7.3	42/0.8
92049.20-22	3705/42.1	1613/17.9	3034/33.7	578/6.4	65/0.7
93008.14-16	3652/41.5	1560/17.7	2979/33.8	538/6.1	50/0.6
94091.10-12	3540/39.2	1782/19.9	2997/33.4	575/6.4	46/0.5

 

Here the left column gives the time of the 2-h period during which the data in the table were accumulated. The table entries give the total number of counts in each of the areas delineated in Figure 5.19, followed by the percentage of the total counts that this represents. The number of counts during the 2h period of the 92009 calibration are about half those during the same length intervals during the other calibrations. This is because the spacecraft telemetry rate was a factor of 2 lower at this time. Another look at the same data can be had from the trackrate files with the program TRACKDUMP. Such a printout for 92049.20-22 is included as Table 5.15 (below). The PHA event counts in W4 (the high energy He channel) are slightly less than the counts found above in the Cm peak for this time. There are several hundred more counts in W3 than were found in the Gd peak. These were probably in the area of W3 that was included in Area A. There are more total PHA counts in W3 and W4 than in W1 and W2, but only 60% more, whereas the rate channels give a He/H ratio of 48:1; this is due to the PHA priority scheme described above. W4 (Cm peak) contains 64.1% of the total counts, W3 (Gd peak) contains 33.8%. The H channels (W1 and W2) each contain only about 1% of the rate counts. One can also check the distribution vs sector from this table: the minimum W4 rate channel counts in sector 8 are 12.4% of the total, the maximum in sector 4 is 12.6%. It is reassuring to look at the Undefined Event Counts and to see that practically all of the PHA event counts in channels W1 and W2 fall outside of the defined track bins. About 15% of the W3 counts are undefined; less than 6% of the W4 counts are.

 

Table 5.15 Track dump output 92049

 

LAN PHA Track Rate Record	Begin time: 92 49 20 0 0
	End time: 92 49 22 0 0

 

PHA event counts

 

Channel	Sector 0	1	2	3	4	5	6	7	8
W0	9026	1128	1128	1128	1128	1128	1128	1128	1130
W1	1383	165	160	170	165	181	171	196	175
W2	2079	275	268	248	252	244	262	261	269
W3	1890	245	242	248	214	232	239	232	238
W4	3673	443	458	462	496	471	456	439	448
W5	0	0	0	0	0	0	0	0	0
W6	1	0	0	0	1	0	0	0	0
W7	0	0	0	0	0	0	0	0	0
W8	0	0	0	0	0	0	0	0	0

 

Rate channel counts

 

Channel	Sector 0	1	2	3	4	5	6	7	8
W0	256106	32300	31955	31884	32009	32168	31959	31966	31863
W1	2099	260	250	247	248	277	254	292	267
W2	3129	382	400	375	382	372	390	409	416
W3	86568	11011	10878	10706	10721	10964	10665	10844	10776
W4	164291	20645	20409	20555	20656	20544	20647	20419	20403
W5	0	0	0	0	0	0	0	0	0
W6	17	0	16	0	1	0	0	0	0
W7	0	0	0	0	0	0	0	0	0
W8	0	0	0	0	0	0	0	0	0

 

Undefined event counts

 

Channel	Sector 0	1	2	3	4	5	6	7	8
W0	0	0	0	0	0	0	0	0	0
W1	0	165	159	169	165	181	169	195	173
W2	0	275	268	247	252	244	262	261	269
W3	0	45	22	26	25	36	34	29	30
W4	0	38	16	21	22	18	22	16	15
W5	0	0	0	0	0	0	0	0	0
W6	0	0	0	0	1	0	0	0	0
W7	0	0	0	0	0	0	0	0	0
W8	0	0	0	0	0	0	0	0	0

 

 

Next: 5.2.4 MFSA Analysis

  

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