AXAF Project Science: Source--detector distances at XRCF

Source-to-detector distances at the XRCF are in meters. Top value of each pair is the distance; bottom, the error in distance. For a HRMA focal length of 10.061 m, the finite-conjugate focus is 10.256 m behind the HRMA node. The HRMA node is 0.018 m behind CAP datum A (on paraboloidal side of Central Aperture Plate).

Note that the DCM source distance depends upon the Bragg glancing angle on the crystal, and thus upon the tuned energy. The algorithm for calculating this distance is

D(ga) = D(45 deg) + (0.030 m) [ csc(2 ga) - cot(2 ga) - 1 ] ,

where ga is the incident Bragg glancing angle and D(45 deg) is the distance for a 45-deg glancing angle. The Bragg glancing angle is related to the x-ray wavelength through

lambda = 2 d sin(ga),

where d is the appropriate lattice spacing for the crystal (12.8784 A for TAP, 3.26643 A for Ge, and 1.35776 A for Si).

	FPC5 ap	SSD5 ap	FPCHN 36	FPCHN ap	FPCH* ap	HRMA node
EIPS spot	37.433	38.199	523.994	524.001	524.316	527.522
	0.005	0.006	0.008	0.008	0.008	0.004
PIGS slit	37.806	38.572	524.367	524.374	524.689	527.895
	0.005	0.006	0.008	0.008	0.008	0.004
HIREFS slit	37.325	38.091	523.886	523.893	524.208	527.414
	0.005	0.006	0.008	0.008	0.008	0.004
DCM spot							TAP	Ge	aSi
ga(degree)							E(keV)	E(keV)	E(keV)
12	38.326	39.093	524.888	524.894	525.209	528.416	2.315	9.128	21.959
	0.006	0.007	0.009	0.009	0.009	0.005
15	38.328	39.094	524.890	524.896	525.211	528.417	1.860	7.332	17.640
	0.006	0.007	0.009	0.009	0.009	0.005
18	38.330	39.096	524.891	524.898	525.213	528.419	1.558	6.141	14.775
	0.006	0.007	0.009	0.009	0.009	0.005
21	38.332	39.098	524.893	524.899	525.214	528.421	1.343	5.296	12.740
	0.006	0.007	0.009	0.009	0.009	0.006
24	38.333	39.100	524.895	524.901	525.216	528.423	1.183	4.666	11.225
	0.006	0.007	0.009	0.009	0.009	0.006
27	38.335	39.101	524.897	524.903	525.218	528.425	1.060	4.180	10.057
	0.006	0.007	0.009	0.009	0.009	0.006
30	38.337	39.104	524.899	524.905	525.220	528.427	0.963	3.796	9.131
	0.006	0.007	0.009	0.009	0.009	0.006
33	38.340	39.106	524.901	524.907	525.222	528.429	0.884	3.484	8.383
	0.006	0.007	0.009	0.009	0.009	0.006
36	38.342	39.108	524.903	524.910	525.225	528.431	0.819	3.229	7.768
	0.006	0.007	0.009	0.009	0.009	0.006
39	38.344	39.110	524.906	524.912	525.227	528.434	0.765	3.016	7.255
	0.006	0.007	0.009	0.009	0.009	0.006
42	38.347	39.113	524.909	524.915	525.230	528.436	0.719	2.836	6.823
	0.006	0.007	0.009	0.009	0.009	0.006
45	38.350	39.116	524.912	524.918	525.233	528.439	0.681	2.684	6.457
	0.006	0.007	0.009	0.009	0.009	0.006
48	38.353	39.120	524.915	524.921	525.236	528.443	0.648	2.554	6.144
	0.006	0.007	0.009	0.009	0.009	0.006
51	38.357	39.123	524.919	524.925	525.240	528.446	0.619	2.442	5.875
	0.006	0.007	0.009	0.009	0.009	0.006
54	38.361	39.127	524.923	524.929	525.244	528.451	0.595	2.346	5.643
	0.006	0.007	0.009	0.009	0.009	0.006
57	38.366	39.132	524.928	524.934	525.249	528.456	0.574	2.263	5.444
	0.006	0.007	0.009	0.009	0.009	0.006
60	38.372	39.138	524.934	524.940	525.255	528.461	0.556	2.191	5.272
	0.006	0.007	0.009	0.009	0.009	0.006
63	38.379	39.145	524.940	524.947	525.262	528.468	0.540	2.130	5.124
	0.006	0.007	0.009	0.009	0.009	0.006
66	38.387	39.154	524.949	524.955	525.270	528.477	0.527	2.077	4.998
	0.007	0.007	0.009	0.009	0.009	0.006

Last Update: 07/01/1997

Name: Steve O'Dell

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