GesSpectre visualises and analyses spectra obtained from nuclear particle detectors. It emulates the display of a multi channel analyser (MCA). The acquisition is made by in an external ADC connected to the Macintosh through a serial RS422 line or with a direct connection to an ADC via a PIA interface. Data can also be read from text files. It is specially oriented to PIXE (Particle Induced X-ray Emission) spectra.
•Up to 9 spectra may be viewed independently and simultaneously in windows.
•Each window has all the Mac usual controls (elevators, grow box, zoom box, etc.).
•The start and stop of an acquisition are controlled by the program and the spectra accumulated in an external device are quickly transferred to memory. Direct connection to an ADC is supported with real time display. All activities are available during acquisitions.
•Each spectrum can be saved in fast compact binary format or as text file.
•Parametric calibration (2nd order) is calculated individually for each spectra.
•Regions of interest (R.O.I.) may be defined anywhere in the spectrum (using only the mouse) and their characteristics instantly presented on the screen. (With a B/W monitor the R.O.I. are presented in bold.)
•On request, the characteristics of the R.O.I. (position, surface, background etc.) are accumulated under a table format, which may be printed, saved on disk (as a “tab separated text file”) or directly transferred into the clipboard (under an Excel™ compatible format).
•The spectrum graphic image may be copied into the clipboard (to be printed or included in a report)
•Automatic processing may be done by creating a "Macro" (a list of commands that could be replayed automatically) and, with the adequate hardware, a sample changer may be controlled.
The program works only with System 7 (or up) and fully conforms to the Macintosh interface. It is written in Think Pascal™ (V4.02) and occupies about 200 kbytes. Pascal sources may be obtained on request.
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EXCERPT FROM THE USER MANUAL
*****MOUSE USAGE
Single click
-above the X axis: move the cursor to the click position,
-below the X axis: toggle the zoom ON/OFF.
Double click
Near a maximum or in a ROI:
-move the cursor to the maximum,
-if not a ROI, make a one channel width ROI,
-beep and display the ROI info in the lower right corner.
Away from a maximum (on a slope e.g.): beep!
Click-drag
-from left to right: mark the underlying channels (define a ROI).
-from right to left: remove the mark (erase a ROI).
*****KEYBOARD SHORTCUTS
Arrows
<Left arrow>: move cursor 1 channel to the left.
<Right arrow>: move cursor 1 channel to the right.
<Opt>-<left arrow>: cursor to right channel of previous ROI (also < and w).
<Opt>-<right arrow>: cursor to left channel of next ROI ( also > and W ).
(if autoscale is on, the Y scale is adjusted on the ROI limits (not maximum).
<Cmd>-<left arrow>: slide spectra half screen to the left.
<Cmd>-<right arrow>: slide spectra half screen to the right.
<Opt>-<Cmd>-<left arrow>: display peak info of previous ROI and move cursor on it.
<Opt>-<Cmd>-<right arrow>: display peak info of next ROI and move cursor on it .
If necessary, readjust viewing area by sliding the spectra left of right.
<Down arrow>: reduce Y scale.
<Up arrow>: increase Y scale.
Other keys
<Space>: adjust Y scale to full scale (during acquisition: twice full scale).
<Enter>: scan ROI and display Peak info (same as: <Opt>-<Cmd>-<right arrow>).
<Tab>: activate next window.
<Esc>: close active window.
<Ctrl>-G: Special beep test.
N.B. :In the comment dialog box of the spectra info window \r is transformed in a <return>.
*****HOW TO CALIBRATE A SPECTRUM?
0.- Clear all ROI (<Cmd>-K).
1.- Select with the mouse some ROI of known energy (min. 1, max. 8).
2.- Choose “Calibration…” in the “Processing” menu.
3.- Replace each proposed value by its exact energy value.
4.- Click OK to calculate the best second order calibration curve of the type
ax^2 + b x + c.
5.- The a, b, c values may be read (or changed) in the “Spectra Info dialog” (cf. display menu).
*****THE MACRO COMMANDS
Each macro command is formed by 3 uppercase letters. The commands have to be written in one sentence. There are 13 commands. The two last ones must be followed be a numerical parameter.
STA Start an acquisition.
STO Stop an acquisition.
ZER Zero the data (on the display and in the ADC buffer).
COP Copy a report into the clipboard.
SAV Save the spectra on disk.
INC Increment the name of the spectra.
PRI Print a report on paper.
TOE Save a report on disk under an Excel™ compatible format.
WAI Wait until the end of an acquisition (preset time or external signal)
OR the end of a step motor displacement.
SMO Smoothing.
TUU Produce a loud beep.
MOV±nnn Move the step motor ±nnn steps (relatively to the actual position).
CYCnnn Recycle the whole Macro from the start nnn times.
•Example:
ZERINCSTAWAISAVTOECYC5MOV-1000CYC10
Repeat 10 times: { Repeat 5 times: { Zero, Increment name, start acq., wait till the end, save data on disk (binary format), save an Excel report file} Move relatively -1000 steps}
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NOTE ON THE EXTERNAL ACQUISITION HARDWARE
By default, the acquisition in GesSpectre is in DEMO MODE. The preference… menu allows to activate another mode:
A.- SERIAL LINK (a.g. Canberra S20 or S35) on modem or printer port.
Bidirectional RS-232 link between the Mac and the ADC box, 8 bits, 9600 bauds (S20) or 19200 (S35), X-on/X-Off protocol.
-A change of the state of the DTR input line stops a running acquisition (external stop).
-On start, the DTR output line flips (to remote control an external apparatus).
B.- Parallel Interface Adaptor (NuBus or PDA) (Cheep — no memory box needed!)
The data lines of the ADC are directly connected to the PIA. During an acquisition, the ADC “pilot signal” activates an interrupt process which reads the result of the conversion from the data line, resets the ADC and increments the designated channel (50% dead time for a counting rate of ≈ 6000 cps on a LC). At low counting rate, the display is updated at every count in real time (this is very useful for low counting rate signal observation).
Some spare lines of the PIA are used to:
-control an external counter: pulse at start,
-move a step motor: one line gives rectangular pulses (max 400 Hz), an other, the direction. During the move, all functions are still active.
-controlling a DAC to change the magnet current.
•GesSpectre works with some National Instruments cards and we have developed a cheap "home made" PDA card for LC and colour classic. (This make a cheap MCA for student lab a.e.) More info on request.
••Caution••
On (old) 68040 Mac, the check for the card is not working and hang the computer when there is no card. (If you did activate the check, you can get out by holding down the option key during boot-up and disabling the option in the preference menu!)
