WBS has spectroscopic capabilities in a wide energy band from soft X-rays to gamma-rays. It consists of a soft X-ray spectrometer (SXS), hard X-ray spectrometer (HXS), gamma-ray spectrometer (GRS), and radiation belt monitor (RBM). Of these, SXS, HXS, and GRS aim at solar flare observations, but RBM serves to sound the alarm for radiation belt passage. All of these detectors have pulse count (PC) data and pulse height (PH) data. PC is the sum of all counts for a given energy range, and PH is essentially an energy loss spectrum as a function of energy. Brief instrument descriptions of SXS, HXS, and GRS are given here. Detailed descriptions can be found in Yoshimori et al., (1991).
SXS consists of two gas proportional counters (SXS-1 and SXS-2) filled with xenon and carbon dioxide (1.16 atm) and has a beryllium window of 0.15 mm thickness. The field of view of each detector is 10 deg x 10 deg. Each of the two detectors covers the photon energy band from 3 keV to 40 keV. SXS-1 has a large effective area which is suitable for detection of small flares, whereas SXS-2 has a small effective area which is suitable for detection of large flares. The energy resolution is about 20 % at 5.9 keV and 12 % at 22 keV. The inflight energy calibration is achieved by detection of 5.9 keV line emitted by a Fe-55 radioactive source. Both SXS-1 and SXS-2 have two PC channels; PC11 and PC12 for SXS-1, and PC21 and PC22 for SXS-2. The first suffix denotes the counter and the latter suffix indicates the energy channels (low; 1 and high; 2). For example, PC12 is the higher energy band of SXS-1. The lower energy bands range from LD to MD1, while the higher energy bands range from MD1 to MD2. These discrimination levels (LD, MD1, and MD2) as well as the gains of the pulse counting electronics circuit (h) and the high tension levels (g) can be independently selected among the four-entry options, respectively.
The discrimination level (y=LD, MD1, and MD2) of the SXS PC channels can be obtained by the following relations.
y(keV) = a * (x +9)/h/g
SXS-1 : a = 0.30
h g LD(x) MD1(x) MD2(x)
00 1.00 1.00 0 40 103
01 0.67 1.36 0 58 127
10 1.47 1.75 0 74 127
11 2.24 2.75 0 91 127
SXS-2 : a = 0.28
h g LD(x) MD1(x) MD2(x)
00 1.00 1.00 0 36 94
01 0.66 1.47 0 54 127
10 1.47 1.87 0 69 127
11 2.15 3.02 0 85 127
The settings were all null (00) before June 18, 1992 and only the gains were changed to g = 01 (for SXS-1 and SXS-2) since then.
The total deadtime of these PC channels is 9 ms. The correction factor is tabulated in the file $DIR_WBS_CAL/dtcorrf.dat.
Distortion of the energy versus pulse-height relationship in the PH mode was found after the launch, which might have resulted from the failure of the pulse-height-analysis electronics circuit. No reliable energy calibration for the PH data is available at the moment.
HXS consists of a NaI(Tl) scintillator (7.6 cm in diameter and 2.5 cm in thickness). The window of NaI scintillator is covered with two kinds of stainless steel absorbers of 13.8 cm2 × 0.08 mm thickness and 31.8 cm2 × 1 mm thickness to suppress low-energy X-rays associated with solar flares.
HXS covers the photon energy band from 20 keV to 650 keV (1991 Oct. 1 - 1992 June 9) and from 24 keV to 830 keV (1992 June 9 - present). The energy resolution is 26 % at 22 keV and 13 % at 88 keV. Inflight energy calibration is achieved by detection of the 60 keV line emitted by an Am-241 radioactive source. In addition, the 191 keV line emitted by radioactive I-123 and the 511 keV line emitted by positron annihilation are used for inflight energy calibration.
HXS has two PC channels PC1 and PC2, and a 128-channel PH. The energy bands of PC1, PC2 and PH are given in the table in section 5.5.
The HXS instrument calibrations are stored in the following data files located in the directory $DIR_WBS_CAL (/ys/wbs/response) and in IDL programs.
| File | Contents |
| Channel number vs. energy relation | |
| hxs_01.rel | (9-Jun-92 - present) |
| hxs_21.rel | (1-Oct-91 - 9-Jun-92) |
| HXS amplification gain was changed on 9 June,1992. | |
| hxs_conv260.rel | Table of 260 incident photon energies for the 260 x 32 response |
| matrices (hxs_01_conv260.resp and hxs_21_conv260.resp) | |
| HXS response matrix (260 rows x 32 columns) | |
| hxs_01_conv260.resp | (9-Jun-92 - present) |
| hxs_21_conv260.resp | (1-Oct-91 - 9-Jun-92) |
| dtcf_pc_hxs.pro | Deadtime correction factor for HXS-PC |
| dtcf_ph_hxs.pro | Deadtime correction factor for HXS-PH |
GRS consists of two identical BGO (bismuth germanate oxide) scintillators (GRS-1 and GRS-2). Each scintillator is 7.6 cm in diameter and 5.1 cm in thickness. The window of each BGO scintillator is covered with a 0.5 mm thick lead absorber to suppress low-energy gamma-rays associated with solar flares. GRS covers the photon energy band from 0.3 MeV to 100 MeV. The energy resolutions is 14 % at 0.662 MeV and 6 % at 4.07 MeV. Inflight energy calibration is achieved by detection of the 1.173 and 1.333 MeV lines emitted by a Co-60 radioactive source. Each GRS has a six-channel PC, a 128-channel PHL and a 16-channel PHH. The energy bands of the PC and PH are given in the table in section 5.5.
The GRS instrument calibration are stored in the following data files located in the directory $DIR_WBS_CAL (/ys/wbs/response) and in IDL programs.
| File | Contents |
| grs1_40.rel | Channel number vs. energy relation for GRS-1 |
| grs2_40.rel | Channel number vs. energy relation for GRS-2 |
| grs1_40_conv260.rel | Table of 260 incident energies for the 260 x 128 |
| response matrix grs1_40_conv260.resp | |
| grs2_40_conv260.rel | Table of 260 incident energies for the 260 x 128 |
| response matrix grs2_40_conv260.resp | |
| grs1_40_conv260.resp | GRS-1 response matrix (260 rows x 128 columns) |
| grs2_40_conv260.resp | GRS-2 response matrix (260 rows x 128 columns) |
| dtcf_ph_grs1l.pro | Deadtime correction factor for GRS-PHL1 |
| dtcf_ph_grs2l.pro | Deadtime correction factor for GRS-PHL2 |
Primary data output of SXS, HXS and, GRS are pulse count (PC) data and pulse height (PH) data. The PC and PH data provide the counting rate time profiles and energy loss spectra, respectively. Each of SXS produces two PC data every 0.25 s (2 s) and a 128-channel PH spectrum every 2 s (16 s) in a high (medium) bit rate mode. HXS produces two PC data every 0.125 s (1 s) and a 32-channel PH spectrum every 1 s (8 s) in the high (medium) bit rate mode. Each of GRS produces six PC data every (0.25 and 0.5 s) and 128-channel PH data every 4 s (32 s) in the high (medium) bit rate mode. The data output of SXS, HXS, GRS and RBM are summarized in the following table.
Time Resolution
WBS Data High bit rate Medium bit rate
--------------------------------------------------------------------------
SXS-1 PC11 (3-15keV*) 0.25 s 2 s
PC12 (15-40keV*) 0.25 s 2 s
SXS-PH1 128 ch (3 - 30 keV*) 2 s 16 s
SXS-2 PC21 (3-15keV*) 0.25 s 2 s
PC22 (15-40keV*) 0.25 s 2 s
SXS-PH2 128 ch (3 - 30 keV*) 2 s 16 s
*The values of energies given above are nominal.
--------------------------------------------------------------------------
(1991 Oct.1-1992 June 9)
HXS-PC1 (20-65keV) 0.125 s 1 s
HXS-PC2 (65-657keV) 0.125 s 1 s
HXS-PH 32 ch (20 - 657 keV) 1 s 8 s
(1992 June 9 - present)
HXS-PC1 (25-75keV) 0.125 s 1 s
HXS-PC2 (75-830keV) 0.125 s 1 s
HXS-PH 32 ch (25 - 830 keV) 1 s 8 s
--------------------------------------------------------------------------
GRS-1 PC11 (0.27-1.04MeV) 0.25 s 2 s
PC12 (1.04-5.47MeV) 0.25 s 2 s
PC13 (5.47-9.3MeV) 0.5 s 4 s
PC14 (9.3-13.1MeV) 0.5 s 4 s
PC15 (8-30MeV) 0.5 s 4 s
PC16 (30-100MeV) 0.5 s 4 s
GRS-PHL1 128ch (0.3-13.1MeV) 4 s 32 s
GRS-PHH1 16 ch (8 - 100 MeV) 4 s 32 s
GRS-2 PC21 (0.3-1.24MeV) 0.25 s 2 s
PC22 (1.24-5.66MeV) 0.25 s 2 s
PC23 (5.66-9.37MeV) 0.5 s 4 s
PC24 (9.37-13.68MeV) 0.5 s 4 s
PC25 (8-30MeV) 0.5 s 4 s
PC26 (30-100MeV) 0.5 s 4 s
GRS-PHL2 128ch (0.3-13.6MeV) 4 s 32 s
GRS-PHH2 16 ch (8 - 100 MeV) 4 s 32 s
--------------------------------------------------------------------------
RBM-SC-PC1 (5 - 50 keV) 0.25 s 2 s
RBM-SC-PC2 (50- 300 keV) 0.25 s 2 s
RBM-PH 32 ch (5 - 300 keV) 1 s 8 s
RBM-SSD (>20 keV) 0.25 s 2 s
If you have any question about WBS software and/or instrument, or if you need any advice in WBS data analyses, contact: