The STOF sensor consists of two subsystems, referred to as the STOF (Suprathermal Time of Flight) and the HSTOF (High Energy Suprathermal Time of Flight).
1. Event Data Definition
1.1. Direct Event Word Definition
The direct event words are generated in the sensor and sent to the DPU via the high speed interface line. These words consist of 48 bits for both STOF and HSTOF events. Bit #47 is the first bit transmitted. The event word format is the same for both subsystems, except for the identifier bits.
# Bit STOF/HSTOF # Bits Remark
47 Format-ID 1 1 Special/Standard (1=Special)
46 Format-ID 0 1 ID STOF/HSTOF (1=STOF)
45..44 Reserved 2 DPU inserts Priority Code: tbd
43 EVS 1 Sensor event selection priority (1=PR)
42.. 41 Gain 2 Gain range of SSD Pixel Detector
40 PRS or PRH 1 POS-Stop, REAR-MCP (1=Set) 39.. 31 SE 9 Sum Energy deposited in the detector
30..27 PFS or PFH 4 POS-START, FRONT-MCP (1=Set)
26..20 POS-SSD 7 SSD Detector Pixel Position
19..10 E 10 Energy Readout of Pixel
9..0 TOF 10 Time of Flight
The identifier indicates whether the direct event word corresponds to a special or standard event, an STOF or HSTOF event. The special events are triggered by the DPU during diagnostic operational mode, the standard direct event is used in the normal, flare and HSTOF neutral operational mode.
The event selection bit EVS is assigned to events like protons at an early stage of the data analysis in the sensor. A TBD fraction of these events is further analyzed and transmitted to the DPU event classification.
The gain bits indicate the setting of the SSD detector gain. The PRS or PRH bit is set as the relevant position of the stop or REAR-MCP is triggered. These bits are ignored by the DPU event classification. However, they are contained in the PHA word in the telemetry.
The SE bits contain the energy sum of the STOF or HSTOF SSD-detector. These bits are ignored by the DPU event classification. They are transferred as a TBD fraction of the telemetry PHA words. The PFS or PFH bits are set as the respective positions of the start or FRONT-MCP are triggered. The POS-SSD contains the location of the pixel of the SSD-detector which is the source of the energy readout value of the event word. The 7 bits are sufficient for encoding the 128 pixels of the STOF and the 64 pixels of the HSTOF section. Both FRONT-MCP and POS-SSD bits are used by the DPU event classification as input for the time of flight pulse height adjustment. E is the energy pulse height signal of the SSD pixel detector and TOF is the pulse height readout of the time of flight.
1.2. Direct Event Transfer Rate
The maximum rate at which direct events are transferred to the DPU is limited by the transfer clock speed of 1,6 msec per bit (625 kHz clock), plus 3,2 msec per event (2 clock periods). The direct event transfer rate is limited in the sensor due to the event processing time of about 100 msec This implies a maximum transfer rate of about 10 kHz for the sum of both the STOF and HSTOF direct events.
1.3. Basic Rates and Monitor Rates
The direct event rates are determined in the sensor. There are 3 basic rates for STOF and 3 basic rates for HSTOF. These basic rates are also defined as STOF or HSTOF sensor priority rates. The priority weighting is TBD and is downloaded into the sensor through the command interface.
The number of monitor rates is TBD (~44). TBD (~4) monitor rates are readout within the same time frame as the basic rates.
The basic and the monitor rates are transferred to the DPU through the command interface on request from the DPU.
1.4. Command Word Definition
The commands are transferred from the DPU to the sensor through the command interface. Some commands are ground commands transferred through the DPU. Other commands are sent by the DPU within fixed time intervals. Others enable the immediate execution of a command sequence in the sensor. These commands are high priority commands, for example the execution command of the high voltage E/Q stepping. In the DPU, the software procedures for these different type of command priorities must be foreseen. The list of the required commands and their format is TBD.
(Preliminary format enclosed).
2. Event Classification Definition
The event classification scheme uses the fast look-up table and addition techniques which establish a correspondence between the measured Time of Flight T and the Energy E for each E/Q step and the stored positions of the M and M/Q surfaces in the T versus E parameter space. The DPU calculates the matrix rates in the M versus M/Q space and classifies the PHA priority of the event.
The E/Q voltage steps and the gain of the SSD pixel detector are the basic parameter for look-up table reevaluation.
2.1. Event Classification Look-Up Tables (Version B. DPU)
The following look-up tables are incorporated in the DPU event classification scheme (STOF and HSTOF are treated as separated sensors and each one is classified within its own classification scheme. The classification schemes of STOF and HSTOF are similar but not identical):
1 Look-up table for TOF pulse height signal correction (STOF and HSTOF)
1 Look-up tables for E pulse height signal POS correction (STOF and HSTOF)
1 Look-up table for log (TA2) (STOF and HSTOF)
1 Look-up tables for log (E) (STOF and HSTOF)
1 Look-up table for the calculation of the M/Q value (STOF)
1 Look-up table and calculation via addition of the M value (STOF and HSTOF)
3 Look-up tables for the
M versus M/Q matrix rates and event classification (STOF)
and the M versus E matrix rates and event classification (HSTOF)
i) High resolution rates ii) Low resolution rates iii) Priority rates
1 High resolution rate counting memory (STOF and HSTOF)
1 Low resolution rate counting memory (STOF and HSTOF)
1 Priority comparator (for the PHA telemetry) (STOF and HSTOF)
2.1.1. Path Length Look-Up Table
The look-up table of path length corrects for the angle deviation of the ion trajectory flight pass. Ion trajectories which are not parallel to the analysis/sensor axis in the first place (angle deviation perpendicular to the E/Q analyzer field, ~5deg.), are corrected within the presented scheme. The 4 position bits of the front MCP and the STOF7 POS-SSD bit (6 bit for HSTOF) of the SSD detector determine 4 discrete angles of the ion flight pass. The table output is a 2 bit word.
2.1.2. SSD Energy Pulse Correction Look-Up Table (SSD Pixel Detector)
This look-up table sets the correction bits of the E pulse height for the variations within the SSD detector subunits (input: 7 bit STOF, 6 bit HSTOF). The tables are recalculated as the SSD detector gain setting is changed (3 gain settings foreseen). The output of the table is the 4 bit POS_E correction word.
2.1.3. Look-up table for log (TA2)
This table determines the corrected log (T^2) of the uncorrected 10 bit TOF pulse height and the 2 bit time of flight pulse height correction out of a 10 x 2 bit table. No recalculation within the E/Q stepping cycle is required. The table output is a 10 bit word.
2.1.4. Look-up tables for log (E)
This table determines the log (E) out of the 10 bit E pulse height and the 4 bit POS_E correction word. Recalculation is required for the 3 gain settings of the SSD detector (addition of some consent C (gain setting) ~ log(gain). The constant is recalculated for each new setting of the SSD detector gain.). The table output is a 10 bit word.
2.1.5. M/Q Look-Up Table
The main STOF M/Q look-up tables calculates the M/Q addresses as a function of the uncorrected TOF pulse height and the E/Q step (*). It is recalculated each 1.25 sec or each sub step of the E/Q stepping scheme (1 x 10 table, output M/Q address). The basic formula is m/q = C(E/Q) . E/Q . T^2. The algorithm is calculating ~ log(m/q), referred as M/Q in the text. The final algorithm is TBD, the proposed algorithm is
M/Q =: log (m/q) = (log(C(E/Q)) + log(E/Q)) + log (T^2), the basis of the log is TBD
(~1,019 or 10^(1/120) => 2 % steps)
The M/Q table output is a 7 bit address word.
(*) Change imposed 1.2.94; MPE: m/q is correct for E/Q (analyser) and measured TOF.
2.1.6. M/E Look-Up Table
The energy pulse height is compressed in a small look-up table to reduce the table size required for the HSTOF M versus E matrix ( 10 bit input address and 4 bit word output).
2.1.7. T versus E Look-Up Tables: M table
The sum of the corrected time-of-flight log(T^2) and log(E) table plus some additional constant, is the mass classification address M. The formula is m = c(T) . E . T^2. c(T) is the solid state detector response function assuming the nuclear defect being dependent on the ion velocity and therefore the corrected time-of-flight T. The final approximation algorithm is TBD, the proposed algorithm is
M =: log (m) = log(c(T)) + log(E) + log (T^2), the basis of the log is TBD (~ 1,009 or
10^(3/1024) => 0,9 % steps for STOF and ~ 1,008 or 10^(4/1024) => 0,3 % steps for HSTOF)
Ensuing the addition of the log(E) and log(T^2), the mass look-up table is a 11 bit (result of the addition of two 10 bit words) by 7 bit (most significant bits of log(T^2) matrix. Therefore some fine-tuning of the mass classification is possible (correction ~ 3% compared to addition algorithm alone). The mass M is classified by an output address word (STOF: 7 bit and HSTOF: 6 bit).
Double coincidence events (no E energy pulse height measured or E=0; no TOF pulse height measured or T=0):
If the measured energy E is zero or E=0, the above formula will still be used in the classification scheme (log(E=0): definition of the E or T under- or overflow within the 11x7 bit matrix)
2.1.8. STOF M versus M/Q and HSTOF M versus E Look-Up Table
The address stored in the M and M/Q tables defines the position of the event in the STOF M versus M/Q look up table. The address stored in the M and compressed E table defines the position of the event in the HSTOF M versus E table. These two 2-D tables are downloaded into the classification scheme.
Table size:
STOF 7 x 7 bit input and high resolution matrix rate address word: 9 bit, low resolution matrix rate address word: 3 bit and priority rates address word: 2 bit.
HSTOF 6 x 4 bit input and high resolution matrix rate address word: 8 bit, low resolution matrix rate address word: 3 bit and priority rates address word: 1 bit.
2.2. Priority and Matrix Rates (DPU)
2.2.1. PHA Priority Rates and Low Resolution Matrix Rates
The low resolution matrix rates and the PHA priority code and rates are determined from the HSTOF M versus E and STOF M versus M/Q Look-up Tables. 4 priority rates are defined for STOF and 2 for HSTOF. The priority code is assigned to the PHA data of the classified direct event. These priority rates cover the whole STOF M versus M/Q matrix and the HSTOF M versus E matrix. The matrix rates are 28 bit words.
The 8 low resolution STOF matrix rates and the 6 HSTOF rates are transferred within the same time interval of 3.75 sec as the priority rates to the telemetry.
2.2.2. High Resolution Matrix Rates
The event is classified via the address given in the STOF M versus M/Q matrix and the HSTOF M versus E matrix. The resulting high resolution matrix rate is incremented. Synchronously with the E/Q stepping, TBD (~4) STOF and one HSTOF high resolution matrix are incremented. ~512 rates for each STOF highresolution matrix and ~ 256 HSTOF matrix rates are foreseen. They are transferred to the telemetry within a TBD multiple of a half stepping cycle. It is foreseen to set the accumulation time and E/Q range via ground command. The matrix rates are 28 bit words.
The event rates decrease as the E/Q stepping is increasing. The M versus M/Q matrix rates of the low E/Q steps should not mask the matrix rates of the high E/Q steps. Therefore the STOF event rates of the low E/Q steps and high E/Q steps are added up in different matrix and summed up for TBD (~4) half cycles.
3. STOF DPU Telemetry Output Format
3.1. Science Data
3.1.1. PHA Data Word Format
The PHA Data Word Format is similar to the direct event word format, except for the additional 7 E/Q step bits and a TBD header. The 7 E/Q step bits are transmitted in the STOF and HSTOF PHA data words. In HSTOF, they are included as an event time identification code. A TBD fraction of the PHA words incorporates the energy sum. A TBD frame is foreseen, i.e. each 10th PHA word.
3.1.2. PHA Priority Scheme
The PHA words are collected within a 1,25 sec or 3,75 sec interval. This time interval is selected via ground command. They are packed in bundles every 15 seconds and transferred to the telemetry. The weighting of the priority classes of STOF and HSTOF and within STOF and HSTOF is TBD. The priority weighting is set on ground command.
The first PHA words fill up the allocated memory space of the PHA telemetry regardless on priority. The second PHA words are restricted to events with middle and high priority class and replace the first group on a one-to-one basis. In the next round the priority is restricted to the next higher priority event class and in the final round to the highest priority class. This process is terminated at any or within any of the four steps at the end of the period between successive readouts.
Example: (exact numbers are TBD)
21 words could be transmitted within 3.75 sec. 15 will be used for STOF, 6 for HSTOF (selectable via ground command). Both STOF and HSTOF have a 21 word memory allocated for their respective PHA words.
STOF: first substep (1.25 see): The first 5 memory words are filled with PHA data, regardless of priority class. Then beginning with the second memory word, the remaining 4 are filled up according to the above scheme. In the third round, the events are replaced starting with the third memory word and the last round starts with the fourth memory word. The first word is most likely filled with an overabundant low priority word, the second one is most likely filled with a word of the next priority class and ...
After the first substep is completed, the next one starts with the same scheme. If the prior substep has not used up his allocated memory space (5 words in this example), the next substep starts with the first empty memory space in the line (pointer). The same applies to the third and last substep.
HSTOF events are handled with a similar scheme, except that the basic period is about 3.75 sec for the 6 PHA words. If at the end of one 3.75 sec period STOF has not used up its allocated memory space, these ones will be occupied then by HSTOF events and vice versa.
3. 1.3. Rates
The basic rates and some monitor rates are transferred to the telemetry each 3.75 see, the other matrix rates each 15 sec. The rates with the "slow" transfer rate are read out on a mod 4 basis in respect to the E/Q step. After 2 cycles or 600 see, one rate for each E/Q step has been transferred to the telemetry.
3.2. Housekeeping Data
The housekeeping data structure is TBD. (Prelimary data sheet is enclosed)
4. Operational Modes
The science and diagnostic modes are selected on ground command, except for the flare mode. Basic parameters as HV stepping range and rates readout period are defined within the DPU software and they could be set via ground command.
4.1. Regular Mode
This is the standard operational mode of the sensor.
4.1.1. Continuous Diagnostic Mode
Continuous analysis of the operational function of the subsystems and packaging in the housekeeping data, i.e. the threshold pattern of the SSD detector unit each 60 sec. These data are read out via the direct event data word channel on command from the DPU. Details are TBD.
4.1.2. Flare Flag Definition
The DPU must check some monitor rates within a TBD time period (~ 5 min). Based on these rates and some TBD procedure, the DPU switches the CELIAS experiment into flare mode. The DPU continues to check the STOF rates and as the switching off procedure applies, CELIAS switches back to normal operation mode with a TBD delay. This ON-OFF procedure is enabled and disabled via ground command.
4.2. Flare Mode
In flare mode, the sensor operates as under regular mode operation conditions except for the enhanced PHA Telemetry rate. (see MTOF DATA Definition, Vers. 1.3)
4.3. HSTOF Neutral Mode
The HSTOF neutral atom detection mode is foreseen. Details TBD (Tables, priority etc.)
4.4. Special Diagnostic Modes
The sensor is switched into the special diagnostic mode via ground command. It should be possible to select several diagnostic submodes on command, for example stimulation and SSD detector read out for diagnostic purposes. Details of required DPU procedures etc. are TBD.
4.4.1. Stimulation
The time of flight and the SSD detector are checked by the internal sensor stimulation set via ground command or within distinct time periods. Further details are TBD.
4.4.2. SSD Detector
The SSD detector readout mode is changed and the telemetry PHA data is used up for checks on the SSD pixel detector subunits. This mode requires up to 15 min and is only used as a trouble shooting mode. Details TBD (Format definition enclosed)
5. STOF/HSTOF Cycle Times
There are 5 natural time periods for the STOF and HSTOF sensor:
300 sec Period for stepping the STOF analyzer HV once up and down. This period is defined as the STOF and HSTOF cycle time.
150 sec Half period of the STOF analyzer high voltage stepping scheme and
accumulation time for the high resolution M versus M/Q matrix
15 sec PHA word and housekeeping telemetry bundles, most monitor rates
3.75 sec Basic rates (40 in 150 see)
1.25 sec STOF analyzer HV sub step (120 in 150 see)
6. Telemetry Structure
6.1. Rate Compression
The fast rates as monitor and basic priority rates are compressed into a 12 bit format. The matrix rates are compressed into a 8 bit format. Details TBD
6.2. Rate Telemetry Structure
The rate telemetry structure is enclosed. Details TBD
6.3. PHA Telemetry Structure
The PHA telemetry bit rate is enclosed. Details TBD
6.4. Housekeeping Data Telemetry Structure
The proposed housekeeping data telemetry structure is enclosed. Details TBD
HSTOF EVENT CLASSIFICATION (PRELIMARY FORMAT, V 1.07 MH)
References: STOF/HSTOF Data Definition Doc. V2.05, STICS Instrument user Manual,
MTOF Data Definition Dec. V 1.3
HSTOF
DPU Input (Physical data used in classification)
Code Bits Range
ch (TOF) 10 0...1023
E or Essd 10 0...1023
MCP POS 4 0...15
SSD-POS 6 0...63
(n (E/Q steps) 7 0..119)
Gain 2 0...2
Corrections: Algorithm and required "implemented" look-up tables *
(* These tables are not recalculated during flight operations. However, if they could be stored in RAM memory and could be downloaded via ground command, this could be useful in cases of partial instrument failure)
Algorithm (a...b)
a) E/Q cut-off
Comment: HSTOF High Voltage setting via ground command, no sweep etc. foreseen.
b) TOF calibration: T# (TOF-channels)
Alg: T#(ch) = A1 * (TOF-channels - A2)
A1: 0.72 (present state of calibration)
A2: 10.18 (offset)
range: 0...700 nsec, cut-off <= ch#11
The time of flight calibration is the same for STOF and HSTOF.
c) log( f_H(T#))
f(_HT#)~ sum (ai. ti)
Polynom or other function (correction for energy loss etc. within C-foil)
d) log( g_H(log(T7^2)))
g_H(log(T7^2)) ~ sum (bi. log(T7^2)i)
Polynom or other function (correction for energy loss etc. within SSD detector).
log(T7^2) are the 7 MSB bits of the log(T7^2) table (see below).
ad c) and d): These polynoms are not necessarily the same as for STOF, as they apply to a different E/Q and E range and another function might fit the data better in this range.
Tables (a...g)
a) SSD gain factor
Tab: G_H = A(i)
Gain: A_H(1) = 1 Offset: C_H(1)=???
A_H(2) = 2/0.3 C_H(2)=???
A_H(3) = (2 / 0.3) * 3 C_H(3)=???
These constants refer to the presently implemented hardware (CAMEX). HSTOF standard operation mode is the gain (3) mode, however, if the neutral particle dection mode is activated, HSTOF should operate in the gain (1 ) or, less probable, gain (2) mode.
b) SSD_G_H (Gain, SSD-POS)
Comments: This table contains the gain * correction of the individual SSD detector pixel (calibration data). The table compresses the 2+6 bit address into a 2+4 bit data word.
Tab: a) SSD_G _H(Gain, SSD-POS )
address (2 bit x 7 bit); data: 2*+4 bit (*) gain: parameter in look-up tables
b) G_H(SSD G_H, gain) (variance of gain)
address: 2*+4 bit;
bits 0...3, *gain parameter (2 bit)
(*) Comment: The offset is corrected in the sensor (since ~ April 93).
c) Pixel_H (SSD POS) Look-Up Table
Comments: This table gives the physical position of the SSD-Pixel within the STOF sensor TOF section. It is required for the ion trajectory correction table.
Tab: Pixel_H (SSD POS)
data: X 0..15 (4 bit), Y 0...3 (2 bit)
AI: up to 10th of August (MPE)
d) Front_H (MCP POS) Look Up-Table
Tab: Front _H(MCP POS)
data: X 0...15 (4 bit)
e) C_H(PL_H# ): PL_H#
Comments: Connection table for ion trajectory path correction. The C_H(i) correction is similar to STOF C(i).
Tab: a) Matrix PL_H#: address (4 x 4 bit), data (2 bit)
Matrix elements:
plii ~ C_H(1);
plij = plji: pli1 ,j ~ C_H(2); pli2,j~C_H(3); pli3,j~C_H(4)
b) constant Matrix: C_H(i),~ 1, 1.02 ,1.04,1.06
f) M - E High Resolution Rates -Selection Table
Comments: This table contains the 8 bit address code of the HR counting memory.
Tab: High Resolution Rates (M- E)
Input range (7x4 bit)
Output 8 bit
g) M - E Low Resolution Rates -Selection Table
Comments: This table contains the 3 bit address code of the HR counting memory.
Tab: Low Resolution Rates (M- E)
Input range (7x4 bit)
Output 3 bit
h) M - E Priority Rates-Selection Table
Comments: This table contains the 1 bit address code of the HR counting memory.
Tab: Priority (M- E)
Input range (7x4 bit)
Output 1 bit
Classification scheme: Fast Look-Up tables (vers. B, 29.4.92 KU Reiche)
Path Length Correction (2.1.1_HSTOF)
Comment: This table calculates the angle deviation of the ion trajectories (max. angle ca. 5deg., PL ~ 1 / cos (angle)). Similar to STOF.
Alg: C_H(PL) = C_H ( PL# {Pixel (SSD POS) o Front (MCP POS) } )
(X4 Bit, Y not used) (X 4bit)
SSD Pixel Energy Correction (2.1.2_HSTOF)
Comment: This table is downloaded for each SSD gain change (calibration data).
Alg: PEC_H (SSD-POS)) = SSD_G_H (Gain, SSD-POS )
address:6 bit; data: 4 bit
Log (T^2) (2.1.3)
Comment: This table calculates the corrected log ( time-of-flight ). The algorithm is the same for STOF and HSTOF.
Alg: LOG(T^2) = A0 + A1 * (2* log (T#(ch) ) + A2 + log (C(PL)))
A0 = constant
A1= factor_1 (factor_1 determines the log basis)
A2= log(factor_2)
T#(ch): as defined above
(PL~ 1...1.1; 2 bit)
Min: ~5-7 nsec, Max:~720 nsec (1023*.7 nsec)
Log (E)_H (2.1.4_HSTOF)
Comment: This table is recalculated for each SSD gain setting. The gain setting is constant for HSTOF (gain mode (3)) except for the neutral particle mode.
Alg: LOG(E)_H = A0 + A1 * (log (Essd+ A2)) + A3 + G_H(gain*, PEC_H(SSD
POS)))
A0= constant
A1 = factor_1 (factor_1 determines the log basis)
A2(gain) = factor 2 (constant offset correction)
A3(gain) = constant gain correction (e.g. = G (gain)
(*) gain: parameter: used only for calculation of table
Correction: G_H: Gain address bits 0..3)
range: <200 keV, 200 keV.... 85 MeV, > 85 MeV, TBD
E# (2.1.6_HSTOF)
Comment: Compression table required for the M-E table
Alg: Log E# = A0 + A1 * Log (E)
A0= constant A1 = factor_1 (factor_1 determines the log basis)
address 10 bit, data 4 bit
M (2.1 7)
Comment: The corrected LOG(T^2) and LOG(E) are added. The result LOG(M#) (11 bits) and the 7 MSB bits of the LOG(T^2)=:log(T7^2) are used in the following table.
(Essd =0, double coincidence must be included in the M-look-up table)
Addition :
Alg: LOG(M#)= AO + A1 * ( log(E)_H+ log (T^2))
AO= constant A1= factor_1 (factor_1 determines the log basis)
log(E)_H: as defined above (corrected Essd)
log(TA2): as defined above (corrected TOF)
Table:
Alg: LOG(M)= AO + A1*log(M#) + A2*log(M#) * log(T7^2) + A3*
(log(M#))^2 + A4*log(T7^2)A3 + A5* g_H(log(T7^2))
g_H(log(T7^2)): polynom or other function, only dependent on
log(T7^2)
(SSD energy loss in Al window and nuclear defect.)
Ai (i=0..5): polynominal factors, determination according to
simulation and calibration programs.
<1,1...80 (Krypton ?), >80
Comment: Double coincidence (Essd =0 -> log(E) =TBD -> address LOG(M) over- or underflow (Reiche, 29.4.92)
Event rate (2.1.8) and Event rate counter (2.2.1 and 2.2.2)
Comment: These tables are downloaded according to the above defined selection tables .
Al: downloaded tables (specifications)
STOF EVENT CLASSIFICATION (PRELIMARY FORMAT, V 1.07 MH)
References: STOF Data Definition Doc. V2.05, STICS Instrument user Manual, MTOF Data Definition Dec. V 1.3
STOF
DPU Input (Physical data used in classification)
Code Bits Range
ch (TOF) 10 0...1023
E or Essd 10 0...1023
MCP POS 4 0...15
SSD-POS 7 0...127
n (E/Q steps) 7 0..119
Gain 2 0...2
Corrections: Algorithm and required "implemented" look-up tables *
(* These tables are not recalculated during flight operations. However, if they could be stored in RAM memory and could be downloaded via ground command, this could be useful in cases of partial instrument failure)
Algorithm (a...b)
a) Uset (n)
Comment: High Voltage setting: Uset -> HV
Uset(n) = A0+A1 * (A2)^(n/119) or similar (table ?)
if Uset(n)< A3 then Uset(n)=A3
if Uset(n)> A4 then Uset(n)=A4
A0: Offset, TBD*
A1: Min: Uset(n=0)); (Min: hardware defined min. E/Q setting)
Uset min = TBD * (~20 keV/q )
A2: Max/Min =50 (Max: = Uset(n=119); hardware defined max.
E/Q step, Max/Min ~ (1 MeV/q / 20 keV/q) )
Uset max = TBD * (~1 MeV/q )
* Sweep HV calibration data (Eberl)
The max. and min. stepping voltage limits are:
A3=: U limit min
A4=: U limit max
STOF EVENT CLASSIFICATION (PRELIMARY FORMAT, V 1.07 MH)
Comment: Umin is not necessarily similar to U limit min. Umax is not necessarily similar to U limit max. The stepping is about 3.33 % per step, indepent of U limit max and U limit min ("cut-off")
b) E/Q stepping: E/Q (n) or EM (Uset(n))
Comments: The analyzer high voltage is incremented in ~3.33 % steps (labeled n, 0....119). E/Q min is 20 keV/q, E/Q max is 1 MeV/q ( or U min is ~2*1 00V, U max is 2 * 5000 V. There are always 120 E/Q steps within 150 sec or one half cycle. The step number is increased in the first half cycle and decreased in the second half cycle. (Stepping n: 0........119, 119......0; 0.....119, 119.....0 etc.). An algorithm is foreseen for the STOF sensor Sweep high voltage set stepping commands (Uset(n)).
Alg: E/Q(n) =E/Q(U set (n)) = f(n) * Uset (n));
f(n)=:constant (n); constant ~ E/Q max / 2*Uset (n max=119)
Comment: constant (n) is assumed to be a constant for standard operation. However, if there is a failure within the HV Supply, similar to the problem which occured within SULEICA (in flight: neg. HV stepping time much greater than calibrated ), a post calibration table constant (n) would be helpful for inflight calibration.
c) TOF calibration: T# (TOF-channels)
Alg: T#(ch) = A1 * (TOF-channels - A2)
A1: 0.7 (present state of calibration)
A2: 1 1 (offset)
0...50 nsec, 50...700 nsec, cut-off <= ch#11
c) log( f(T#))
f(T#)~ sum (ai. ti)
Polynom or other function (correction for energy loss etc. within C-foil)
d) log( g(log(T7^2)))
g(log(T72)) ~ sum (bi. log(T7^2)i)
STOF EVENT CLASSIFICATION (PRELIMARY FORMAT, V 1.07 MH)
Polynom or other function (correction for energy loss etc. within SSD detector).
log(T72) are the 7 MSB bits of the log(T7A2) table (see below).
Tables (a...g)
a) SSD gain factor
Tab: G = A(i)
Gain: A(1) = 1 Offset: C(1)=???
A(2) = 2/0.3 C(2)=???
A(3) = (2 / 0.3) *3 C(3)=???
These constants refer to the presently implemented hardware (CAMEX).
b) SSD_G (Gain, SSD-POS), G1 () and G2()
Comments: This table contains the offset and gain * correction of the individual SSD detector pixel (calibration data). The table compresses the 2+7 bit address into a 2+4 bit data word.
Tab: a) SSD_G (Gain, SSD-POS )
address (2 bit x 7 bit); data: 2*+4 bit (*) gain: parameter in look-up tables
b) G(SSD_G, gain) (variance of gain)
address: 2*+4 bit;
bits 0...3 *gain parameter (4 bit)
(*) The offset is corrected in the sensor (since ~ April 93). G contains constant matrix elements.
c) Pixel (SSD POS) Look-Up Table
Comments: This table gives the physical position of the SSD-Pixel within the STOF sensor TOF section. It is required for the ion trajectory correction table.
Tab: Pixel (SSD POS)
data: X 0..15 (4 bit), Y 0...7 (3 bit)
Al: up to 10th of August (MPE)
STOF EVENT CLASSIFICATION (PRELIMARY FORMAT, V 1.07 MH)
d) Front (MCP POS) Look Up-Table
Tab: Front (MCP POS)
data: X 0...15 (4 bit)
e) C(PL# ): PL# and C
Comments: Connection table for ion trajectory path correction
Tab: a) Matrix PL#: address (4 x 4 bit), data (2 bit)
Matrix elements:
plii ~ C(1 ); plij = plji: pli1 ,j ~ C(2); pli2,i~c(3); pli 3 j~C(4)
b) constant Matrix: C(i) ~ 1, 1.02 ,1.04, 1.06
f) Stepping address matrix (M/Q-M)-E/Q(n) (see also 2.2.2.)
Comment: Compression of r the 7 bit E/Q steps in a 2 bit data word (address bits for the high resolution counter. Required to minimize interference of low and high E/Q steps within the M-M/Q matrix)
Alg: (M/Q-M)-E/Q(n) = f (n)
address 7 bit, data 2 bit
g) M/Q - M High Resolution Rates-Selection Table
Comments: This table contains the 9 bit address code of the HR counting memory.
Tab: High Resolution Rates (M/Q - M)
Input range (7x7 bit)
Output 9 bit
h) M/Q- M Low Resolution Rates -Selection Table
Comments: This table contains the 3 bit address code of the HR counting memory.
Tab: Low Resolution Rates (M/Q- M)
Input range (7x7 bit)
Output 3 bit
STOF EVENT CLASSIFICATION (PRELIMARY FORMAT, V 1.07 MH)
i) M/Q- M Priority Rates-Selection Table
Comments: This table contains the 2 bit address code of the HR counting memory.
Tab: Priority (M/Q- M)
Input range (7x7 bit)
Output 2 bit
Classification scheme: Fast Look-Up tables (vers. B. 29.4.92 KU Reiche)
Path Length Correction (2.1.1)
Comment: This table calculates the angle deviation of the ion trajectories (max angle cat. 5deg., PL ~ 1 / cos (angle))
Alg: C(PL) = C ( PL# {Pixel (SSD POS) o Front (MCP POS) } )
(X4 Bit, Y not used) (X 4bit)
SSD Pixel Energy Correction (2.1.2)
Comment: This table is downloaded for each SSD gain change (calibration data).
Alg: PEO (SSD-POS)) = SSD_OG (Gain, SSD-POS )
address:7 bit; data: 4 bit
Log (T^2) (2.1.3)
Comment: This table calculates the corrected log ( time-of-flight ).
Alg: LOG(T^2) = A0 + A1 * (2* log (T#(ch) ) + A2 + log (C(PL)))
A0 = constant
A1= factor_1 (factor_1 determines the log basis)
STOF EVENT CLASSIFICATION (PRELIMARY FORMAT, V 1.07 MH)
A2= log(factor 2)
T#(ch): as defined above
(PL~ 1...1.1; 2 bit)
Min: ~5-7 nsec, Max: ~720 nsec (1023*.7 nsec)
Log (E) (21 4)
Comment: This table is recalculated for each SSD gain setting.
Alg: LOG(E)= A0 + A1 * (log (Essd+ A2 )) + A3+G(gain*,PEC(SSD-POS)))
A0= constant
A1 = factor_1 (factor_1 determines the log basis)
A2(gain) = factor_2 (constant offset correction)
A3(gain) = constant gain correction (e.g. = G (gain)
(*) gain: parameter: used only for calculation of table
Correction: G: Gain address bits 0..3
range: <20 keV, 20 keV.... 26 MeV, > 26 MeV
M/Q (2.1.5)
Alg: LOG(M/Q)= A0 + A1 * ( log(E/Q(n) + A2) + log(f(T#(ch))) + 2 log T#(ch) )
A0= constant
A1 = factor_1 (factor_1 determines the log basis)
A2= factor_2 (energy-loss within C-foil etc.)
E/Q(n) as defined above (energy/charge stepping)
f(T#(ch)): polynom or other function, only dependent on T#(ch)
(energy loss and nuclear defect in C-foil)
T#(ch) as defined above (uncorrected TOF)
range: <1, 1...80, >80
M (2.1 7)
Comment: The corrected LOG(T^2) and LOG(E) are added. The result LOG(M#) (11 bits) and the 7 MSB bits of the LOG(T^2)=:log(T7^2) are used in the following table. (Essd =0, double coincidence must be included in the M-look-up table)
Addition:
ALG: LOG(M#)= AO + A1 * ( log(E)+ log (T^2))
AO= constant
A1 = factor_1 (factor_1 determines the log basis)
log(E): as defined above (corrected Essd)
log(T^2): as defined above (corrected TOF)
Table:
Alg: LOG(M) = AO + A1*log(M#) + A2*log(M#) * log(T7^2) + A3*
(log(M#))^2 + A4*log(T7^2)^3 + A5* g(log(T7^2))
g(log(T7^2)): polynom or other function, only dependent on
log(T7^2)
(SSD energy loss in al window and nuclear defect.)
Ai (i=0..5): polynominal factors, determination according to
simulation and calibration programs.
<1,1...60 (Krypton ?), >80
Comment: Double coincidence (Essd =0 -> log(E) =TBD -> address LOG(M) over- or underflow (Reiche, 29.4.92)
Event rate (2.1.8) and Event rate counter (2.2.1 and 2.2.2)
Comment: These tables are downloaded according to the above defined selection tables . The high resolution matrix rates are incremented synchronously with the E/Q stepping, i.e. 4 STOF high resolution matrix are incremented depending on the E/Q step setting. Therefore the low E/Q steps do not interfere with the high E/Q steps within the M- M/Q matrix. The address of the high resolution event rate counter is therefore 9+2 bit. The 2 bit are stored in a table called stepping matrix (M/Q-M)-E/Q(n).
Al: downloaded tables (specifications)