;
; This document describes the elements in the X-ray path in the HESSI croystat.  It includes
; the beryllium windows and Mylar within the cryostat.
;
;
; Here is an email from April 1999 from Paul Turin on the mylar in the X-ray path within the cryostat.

;Richard,
;I think I finally have the correct cryostat blanket info. Blanketing in
;front of the detectors is as following (going in the direction of X-ray
;travel):
;
;Outer shield blankets:
;
;1-mil mylar, VDA 1 side
;1/4-mil mylar, VDA 2 sides
;1/4-mil mylar, VDA 2 sides
;
;1/4-mil mylar, VDA 2 sides
;1/4-mil mylar, VDA 2 sides
;
;1/4-mil mylar, VDA 2 sides
;1-mil mylar, VDA 1 side
;                                                                                  
;Inner shield blanket:
;
;1-mil mylar, VDA 1 side
;8 layers 1/4-mil mylar, VDA 2 sides
;1-mil mylar, VDA 1 side
;
;All netting has cutouts over detectors.
;
;Total material in path = 7.25 mils mylar 
;VDA = Vapor-Deposited Aluminum, Angstroms thick
;
;
;Paul Turin
;Space Sciences Lab
;U.C. Berkeley
;pturin@ssl.berkeley.edu
;
; 7.25 mils mylar = .002192 *  gm/cm2/mil * 7.25 mils of carbon
; 	plus
;		    .001168 * gm/cm2/mil * 7.25  mils of oxygen
; 
; at http://www.filmcapacitors.com/dielect.htm
; we find the density of Polyester(Mylar) given as 1.395
; Using the densities above,
;IDL> print,(.002192+.001168)*1000./2.54     
;      1.32283
; So we are at least close to a standard value. Whew!

; The filter plus blanket transmisson can be calculated in each of the four states by using
; this file and HESSI_FILTERS()
; For a set of energies, <emdges>, in keV greater or equal to 3 keV. And where <file> is the
; full path to this file.
;
;
;The following is the data structure used to describe all of the elements in the X-ray path.
;The thickness units default is 'cm', although 'mils' is most commonly used.
;Presently, only 'mils' is recognized as an alternative to a blank string. 
;The id tag means, 0- fixed in path, 1- part of shutter_10 (Thin/B), 2-part of shutter_01(Thick/A).
;  
;hessi_win = { hessi_win5, fraction:fltarr(5), regions:intarr(5), layers: intarr(2), $
;	thickness: fltarr(2), units:'', z:0, id:0} 

; Define the fractional areas of 4 regions defining the X-ray path cross-section.
; These are the fractional values seen in the lines defining the material in each layer and segment.
;0.850, .050, .0874, 0.012, 0.0006 ;frac1, frac2, frac3, frac4, frac5
;
;0.833207,    0.0841974,    .06975,   0.01178,   0.001063 ;frac1, frac2, frac3, frac4, frac5 disc9
1.0,         0.0,         0.0,       0.0,       0.0      ;frac1, frac2, frac3, frac4, frac5 disc9



;Cryostat windows, all regions, 20 mil entrance window + 10 mil can window + two 5 mil internal thermal barriers of Be.

frac1, frac2, frac3, frac4, frac5, 1, 1, 1, 1, 1,      1, 1,   40.,  40.,  mils,  4,  0 


;Cryostat mylar, all regions,  7.25 mil mylar, carbon
frac1, frac2, frac3, frac4, frac5, 1 1, 1, 1, 1,       1, 1,  .015892, .015892,  gmcm2,  6,   0 

;Cryostat mylar, all regions,  7.25 mil mylar, oxygen
frac1, frac2, frac3, frac4, frac5, 1 1, 1, 1, 1,       1, 1,  .008468, .008468,  gmcm2,  8,   0 

;Summary of text read into structure hesi_win5 structure.
;** Structure HESSI_WIN5, 7 tags, length=72:
;   FRACTION        FLOAT     Array[5]  - fractional area in each of 5 regions
;   REGIONS         INT       Array[5]  - 1 indicates region populated with this material. 0 empty.
;   LAYERS          INT       Array[2]  - minimum and maximum number of layers
;   THICKNESS       FLOAT     Array[2]  - minimum and maximum thickness in UNITS
;   UNITS           STRING    ''	- UNITS mils or gmcm2 (gms/square cm)
;   Z               INT              0  - Z of material
;   ID              INT              0  - Association ID.