ORTEC DSPEC Hardware Manual
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ORTEC DSPEC Hardware Manual

Digital gamma-ray spectrometer
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69;,*
®
®
DSPEC
Digital Gamma-Ray Spectrometer
Hardware Manual
Printed in U.S.A.
ORTEC Part No. 761560
0303
Manual Revision G

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  • Page 1 69;,* ® ® DSPEC Digital Gamma-Ray Spectrometer Hardware Manual Printed in U.S.A. ORTEC Part No. 761560 0303 Manual Revision G...
  • Page 2 ORTEC fails to manufacture or deliver items called for in this agreement or purchase order, ORTEC’s exclusive liability and buyer’s exclusive remedy shall be release of the buyer from the obligation to pay the purchase price. In no event shall ORTEC be liable for special or consequential damages.

  • Page 3: Table Of Contents

    1.1. What is DSPEC? ........
  • Page 4 ® DSPEC Digital Gamma-Ray Spectrometer 6. COMMANDS AND RESPONSES ..........21 6.1.

  • Page 5: Safety Instructions And Symbols

    Safety Instructions and Symbols This manual contains up to three levels of safety instructions that must be observed in order to avoid personal injury and/or damage to equipment or other property. These are: DANGER Indicates a hazard that could result in death or serious bodily harm if the safety instruction is not observed.

  • Page 7: Introduction

    DSPEC combines all the best features of low- and high-rate analog systems in a single, PC- based package that is easily connected to local area networks (LANs). This highly automated, yet flexible, hardware and software combination is suitable for most spectroscopy applications.

  • Page 8: What Is Dspec

    Digital Gamma-Ray Spectrometer 1.1. What is DSPEC? One germanium or silicon gamma or x-ray detector, one PC, and one DSPEC comprise a complete spectroscopy system. The detector provides a signal proportional to the gamma-ray energy; the PC provides the user interface, data display, and storage; and the DSPEC provides everything else.

  • Page 9: Getting Started

    2.1. What You Will Learn in this Chapter In this chapter you will:  Become acquainted with the DSPEC front- and rear-panel indicators and controls.  Set the electrical power input for your local conditions.  Learn whether you need to change the factory settings of the internal switches.

  • Page 10: The Rear Panel

    The POWER switch turns the instrument on or off and indicates its status with a lighted indicator. 2.3. The Rear Panel Figure 2 shows the DSPEC rear panel. Fig. 2. DSPEC Rear Panel.

  • Page 11: Internal Switches

    2.4. Internal Switches NOTE If you are using P-type detectors, such as ORTEC’s GEM Series, or if you have purchased a complete system, you may skip the remainder of this section. There are two internal settings which must be correctly set for your particular type of detector.
  • Page 12 1. Remove the cover as described above. 2. Turn the DSPEC so that its right side (opposite the power supply and fan) faces you. 3. The high-voltage power supply board is the bottom board in the stack of four boards.
  • Page 13 2. GETTING STARTED Fig. 3. Internal Details and Amplifier Input Polarity Switch. Moving one jumper location from the edge of the board toward the center selects negative or positive bias. The jumpers closest to the edge of the high-voltage power supply board select positive voltage;...

  • Page 14: Internal Battery

    Digital Gamma-Ray Spectrometer Fig. 4. Bias Selector Board (BSB). 2.5. Internal Battery An internal lithium battery provides backup of settings when the power to the unit is off. Should the battery become depleted, replace it with ORTEC Part Number 739460.

  • Page 15: System Connection

    4. Connect the Preamplifier Energy Output to the DSPEC rear-panel INPUT connector. The cable used is normally 100- coaxial cable with BNC type connectors. 5. Connect the data link from the DSPEC to the computer. The normal connection is Ethernet standard 50- cable with BNC type connectors. Alternatively, the ORTEC Dual-Port Memory connection can be used.

  • Page 16: Multiple Detectors

    3. Move the jumper to the desired address. Address 1 is represented by the two pins closest to the outside edge of the DSPEC. Address 8 is represented by the two pins closest to the center of the DSPEC. Figure ? shows the appropriate jumper location for each address.

  • Page 17: Theory Of Operation

    4. THEORY OF OPERATION 4.1. What You Will Learn in this Chapter:  Briefly review a high purity germanium (HPGe) gamma-ray spectroscopy system.  Learn how a shaping amplifier controls the tradeoffs between energy resolution and data rate in an HPGe system.  Compare analog and digital spectroscopy systems.

  • Page 18: Analog Vs. Digital

     Changing the shaping time in the analog system involves mechanical switches changing several components. Consequently, the number of shaping times available is limited. The shaping time in the digital system is determined by constants in the DSPEC computer code and can be changed at will. Many more values are available.
  • Page 19  The reference baseline in analog systems varies with count rate. This causes peaks in the spectrum to shift and broaden. Digital systems have no such effects. Again, as most of the DSPEC is digital, such problems are vastly reduced.
  • Page 20 ® DSPEC Digital Gamma-Ray Spectrometer...

  • Page 21: Specifications

    1.7 mV/keV such specifications are DSPEC SYSTEM specifications. Comparison should be DSPEC converts the VOLTAGE output signal from a charge- made ONLY with SYSTEM sensitive preamplifier into a count in a memory location of the histogram memory. This conversion follows the relationship: specifications in the analog world.
  • Page 22 ® DSPEC Digital Gamma-Ray Spectrometer System Conversion Gain The overall gain of the system is appropriate for use with all types of Ge detectors.  Coaxial “GEM” (P-type) and “GAMMA-X” (N-type).  Low Energy “LO-AX” (low-energy coaxial), “GLP” (planar Ge), “IGLET” and “IGLET- X”...

  • Page 23: Indicators

    5. SPECIFICATIONS 1 (2 billion) counts per Data Memory 16384 channels of non-volatile data memory; 2 channel. Presets Multiple presets may be set on any or all of the following:  Statistical Allows setting the required statistical accuracy on a key peak (for example, stop counting when the activity of Co is known to be better than 5%).

  • Page 24: Inputs And Outputs

    REMOTE SHUTDOWN Rear-panel BNC is used to turn off the bias supply voltage in the event that the detector warms up. This remote shutdown is compatible with any ORTEC detector. The REMOTE SHUTDOWN must be connected to the Bias Shutdown of the detector, or the high voltage will not turn on.

  • Page 25: Controls

    5. SPECIFICATIONS NOTE THESE REMOTE SHUTDOWN PROPERTIES: An open circuit applied to the REMOTE SHUTDOWN input indicates a warm detector; therefore, the high voltage is turned off. Drawing a current of 500 µA from the REMOTE SHUTDOWN input indicates a cool detector; therefore, the high voltage can be turned on. The REMOTE SHUTDOWN input is clamped at 700 mV by an internal clamp.

  • Page 26: Prerequisites

    ® DSPEC Digital Gamma-Ray Spectrometer 5.3. Prerequisites 5.3.1. Hardware ® ® ® A IBM -compatible PC capable of running Microsoft Windows for Workgroups 3.11 is required. Windows for Workgroups requires a 386 or higher processor, 8 megabytes (MB) of RAM, and a 100-MB hard disk. At least 12 MB of RAM are recommended. For Ethernet, an operating Windows for Workgroups network is required.

  • Page 27: Commands And Responses

    6. COMMANDS AND RESPONSES Communication with a DSPEC consists of sending command records to the MCB and receiving response records from the MCB. Both command and response records consist of a sequence of printable ASCII characters followed by an ASCII carriage return. The single exception to this rule is the “#B”...

  • Page 28: Percent Response Records

    The macro error code represents the general class of error with 0 meaning no error, and the micro error code represents the sub-class of error with 0 meaning no error. Following is a list of all percent responses for the DSPEC. Unconditional Success: %000000069<CR>...
  • Page 29 6. COMMANDS AND RESPONSES %000038080<CR> Device preset already exceeded and High Voltage not enabled. The command was ignored. %000054078<CR> Device preset already exceeded, High Voltage not enabled and amplifier was not pole-zeroed. The command was ignored. Power-Up Alert: Power-up just occurred and the selftest results are: %001000070<CR>...

  • Page 30: Dollar Response Records

    ® DSPEC Digital Gamma-Ray Spectrometer Command not allowed while acquisition in progress. %131135083<CR> %131136084<CR> Command not allowed in current mode of operation. %131137085<CR> Hardware failure detected while processing command. 6.3. Dollar Response Records SHOW and STEP commands respond with a single dollar response record followed immediately by a percent response record.
  • Page 31 6. COMMANDS AND RESPONSES In the following catalog, the commands are listed in alphabetical order, each starting with a command prototype line. Upper-case letters, numeric digits, blank spaces, and special symbols such as the underscore ( _ ) and comma ( , ) in the prototype line are literal text to be sent to the MCB exactly as they appear.
  • Page 32 Prepares the serial line for communication with a computer. In computer mode, text sent to the DSPEC does not echo back to the host, and response records sent to the host by the DSPEC are terminated only with a carriage return (no accompanying line feed). This command has no effect when sent via the mailbox.
  • Page 33 See also SHOW_GAIN_STABILIZATION. DISABLE_HV Turns off the high-voltage output on the rear panel of the DSPEC. Note that with no external load on the high-voltage output it takes approximately 60 seconds for the high voltage to drop to zero volts. See the section on the bias supply for more information about the high- voltage output.
  • Page 34 SHOW_GAIN_STABILIZATION, and INITIALIZE_GAIN_STABILIZATION. ENABLE_HV Turns on the high-voltage output on the rear panel of the DSPEC. The voltage selected on the rear panel will be present on the high-voltage output within 60 seconds after this command is received unless the output is overloaded or the output is shut down by the high- voltage shutdown.
  • Page 35 Enables the recognition of commands on the alternate communication path. If this command is sent to the DSPEC via the mailbox it enables command recognition on the serial line. If this command is sent via the serial line it enables command recognition in the mailbox.
  • Page 36 Reboots the MCB. This command is not normally used and may terminate communication. MCB returns a 000130. RESET Resets the DSPEC to the state just after power is applied. This command responds with a % response that indicates power-up just occurred.
  • Page 37 2 resets the digital signal processor (DSP) chips. This command is only used for test purposes. RESET_REMOTE Resets any UART error conditions when sent to the DSPEC via the mailbox. Resets mailbox communications when sent to the DSPEC via the serial communications path. SAMPLE Sending this command causes another waveform to be captured in InSight mode.
  • Page 38 ® DSPEC Digital Gamma-Ray Spectrometer SET_DATA [start, chans],value If the optional start and chans parameters are included in this command, the range of channels specified by start and chans is loaded with value. Sets all channels of spectral data in the window of interest (see SET_WINDOW command) for the currently selected device (see SET_DEVICE command) to the specified count.
  • Page 39 6. COMMANDS AND RESPONSES SET_DEVICE device This command is provided for compatibility with the Model 919. Only device number 1 is valid for a DSPEC. SET_DSP num, command,value This is a debugging command that can be used to directly modify parameters within the digital signal processor chips.
  • Page 40 ® DSPEC Digital Gamma-Ray Spectrometer SET_GAIN_CONVERSION chans Sets the conversion gain. The conversion gain defines the number of channels within the device that will used for spectral data. This has the effect of altering the resolution of the ADC from 14 bits (conversion gain = 16384) to 9 bits (conversion gain = 512) for the device.
  • Page 41 Causes the DSPEC to expect the ADC gate input signal in coincident mode. See also SET_GATE_OFF, SET_GATE_ANTICOINCIDENT, and SHOW_GATE. SET_GATE_OFF Causes the DSPEC to ignore the state of the ADC gate input signal. See the section on the ADC gate input for more information. See also SET_GATE_COINCIDENT, SET_GATE_ANTICOINCIDENT, and SHOW_GATE.
  • Page 42 Establishes the Ethernet address used by the 83905 Ethernet chip. The company portion of the address is usually not included causing the ORTEC ID (41020) to be used. The addr portion should not be the same on any two MCBs connected to the network. This address is...
  • Page 43 DSPEC. Setting a peak preset to 0 counts disables the preset. The peak preset may be set to from 0 (disabled) to 2147483647 counts. See also CLEAR_PRESETS and SHOW_PEAK_PRESET.
  • Page 44 This command is provided for compatibility with other ORTEC MCBs. It specifies that binary records are to be used by the WRITE command for sending spectral data to the host computer via the serial line. This is the only radix supported by the DSPEC. SET_ROI start_chan,number_of_chans Sets the ROI flags for the specified channels.
  • Page 45 6. COMMANDS AND RESPONSES SET_SEGMENT number Provided for compatibility with Model 918-type MCBs. This command has no effect for the DSPEC. The segment number may be any value from 1 through 16. Execution Errors: %131128085<CR> The specified segment number was either zero or a value greater than 16.
  • Page 46 Sets the true-time counter to the specified number of ticks. The number represents true time in units of 20 milliseconds (50 ticks per second). Normally this value is set by the DSPEC during data acquisition. See also CLEAR_COUNTERS and SHOW_TRUE.
  • Page 47 6. COMMANDS AND RESPONSES Legal Commands: SET_WIDTH 0<CR> Width set to default (512). SET_WIDTH 12<CR> Width set to minimum value of 12 bytes. SET_WIDTH 512<CR> Width set to maximum value of 512 bytes. SET_WINDOW [start, length] Sets the window of interest to the specified start channel and number of channels. The channels of spectral data in the window of interest are affected by commands such as LEAR, SET_DATA, and WRITE.
  • Page 48 (3 channels) or would be outside the devices range. %131136084<CR> The command was attempted while zero stabilization was enabled. SHOW_ACTIVE Returns a 1 if the DSPEC is active (i.e., acquiring spectral data) or 0 if it is not active. Responses: $C00000087<CR> Not active. $C00001088<CR>...
  • Page 49 Returns a record that indicates the hardware configuration of the MCB. The record contains information about the number of segments in an MCB device (always 1 for the DSPEC), and the current conversion gain for each segment. The record is organized as follows:...
  • Page 50 ® DSPEC Digital Gamma-Ray Spectrometer from 001–031, month as a 3-digit integer number from 001–012, and year as a 3-digit integer number from 000–099. See also SET_DATE_START. Responses: $N001001088052<CR> Date reported as Jan 1, 1988. $N031012099059<CR> Date reported as Dec 31, 1999.
  • Page 51 6. COMMANDS AND RESPONSES SHOW_DELAY_SAMPLE Shows the Delay Sample setting. See also SET_DELAY_SAMPLE. Responses: $C00003090 The sample number is 00003, and 090 is the checksum. SHOW_DEVICE Returns the number of the currently selected device (see SET_DEVICE command). See also START and STOP. Responses: $A001246<CR>...
  • Page 52 Gain channel is channel 16382 (highest possible channel). SHOW_GAIN_COARSE Returns the coarse gain for the DSPEC internal amplifier. In operation, the resulting signal gain is the product of the coarse gain, the fine gain, and the super-fine gain (used by stabilizer).
  • Page 53 6. COMMANDS AND RESPONSES $C00010088<CR> Coarse gain reported as 10. $C00020089<CR> Coarse gain reported as 20. $C00050090<CR> Coarse gain reported as 50. $C00100088<CR> Coarse gain reported as 100. SHOW_GAIN_CONVERSION This command returns the conversion gain. Responses: $C00512095<CR> Conversion gain reported as 512 channels. $C01024094<CR>...
  • Page 54 ® DSPEC Digital Gamma-Ray Spectrometer Responses: $C00001088<CR> Gain width has not been set. $C00003089<CR> Gain width is 3 channels (lowest possible width). $C00256100<CR> Gain width is 256 channels (highest possible width in Gauss mode). $C16383108<CR> Gain width is 16383 channels (highest possible width in point mode with gain channel set to 8192).
  • Page 55 6. COMMANDS AND RESPONSES SHOW_INTEGRAL [start_chan,number_of_chans] Reports the sum of the specified group of spectral data channels. If start_chan and number_of_chans is not provided, SHOW_INTEGRAL reports the sum of all channels in the currently selected segment that have their ROI flag set. Responses: $G0000000000075<CR>...
  • Page 56 ® DSPEC Digital Gamma-Ray Spectrometer Responses: $G0000000000075<CR> Live-time preset reported as disabled. $G0000000001076<CR> Live-time preset reported as 1 tick. $G4294967295132<CR> Live-time preset reported as 4294967295 ticks. SHOW_LIVE_REMAINING Reports the current live-time remaining in units of 20 milliseconds (50 ticks per second). See also SET_LIVE_REMAINING.
  • Page 57 Returns in a $H record the Ethernet address used by the 83905 Ethernet chip. The address is composed of a 32-bit company portion of the address which is usually set to the ORTEC ID (41020) followed by the address portion. See also SET_NETWORK_ADDRESS.
  • Page 58 ® DSPEC Digital Gamma-Ray Spectrometer SHOW_OVERFLOW_PRESET Reports the state of the overflow preset. Responses: $IT<CR> Overflow preset enabled. $IF<CR> Overflow preset disabled. SHOW_PAGE See also SET_PAGE. Responses: $A001246 Page number 1. SHOW_PEAK This command returns the contents of the ROI channel with the largest number of counts. An ROI channel is a channel that has the ROI flag set.
  • Page 59 Reports the PZ Delay setting. See also SET_PZ_DELAY. Responses: $C00075099 SHOW_RADIX This command is for compatibility with other ORTEC MCBs. It always reports that the number base radix for the WRITE command is binary. Responses: $FBIN<CR> Number base set to binary radix.
  • Page 60 Response: $D0700000050ccc Calculation is performed on channels 7000–7049. SHOW_SEGMENT This command is for compatibility with other ORTEC MCBs. It reports the last value that was set with the SET_SEGMENT command. Segments have no meaning in DSPECs. Responses: $A001246<CR> Segment last set to 1.
  • Page 61 6. COMMANDS AND RESPONSES SHOW_SHAP_FLAT Reports the width of the flattop in µs. See also SET_SHAP_FLAT. Responses: SHAP_FLAT 0000000000001.2 SHOW_SHAP_RISE Displays the Rise Time setting in µs. See also SET_SHAP_RISE. Responses: SHAP_RISE 0000000000003.2 SHOW_SNUM Responds with a $F record indicating the serial number of the MCB. See SET_SNUM. Responses: $F100 Serial Number = 100.
  • Page 62 ® DSPEC Digital Gamma-Ray Spectrometer SHOW_THRESHOLD_NEGATIVE See also SET_THRESHOLD_NEGATIVE. Responses: THR_NEG 0000379791 Negative threshold is 379791. SHOW_THRESHOLD_POSITIVE See also SET_THRESHOLD_POSITIVE. Responses: THR_POS 00000126811 Positive threshold is 126811. SHOW_THRESHOLD_SAMPLE See also ENABLE_THRESHOLD_SAMPLE, SET_THRESHOLD_SAMPLE. Responses: THR_DIS 00000000003 Threshold set to 3 and disabled.
  • Page 63 Returns the current uncertainty preset setting. See also SET_UNCERTAINTY_PRESET. Responses: UNCE_PRES 000000000000000 No preset. UNCE_PRES 0000000000008.5 Preset set to 8.5%. SHOW_VERSION Reports the DSPEC firmware Version number in the form Fmmmm-vvv<CR> where mmmm is a 4-character model designator and vvv is a 3-character version designator.
  • Page 64 Example Responses: $FDSPE–002<CR> Model DSPEC firmware Version 2 reported. SHOW_WIDTH Reports the maximum number of bytes that may be sent by the DSPEC to the host computer as a result of the WRITE command. See also SET_WIDTH and WRITE. Responses: $C00012090<CR>...
  • Page 65 START [seg-mask] Starts the acquisition of spectral data. The optional segment mask is provided for compatibility with other MCBs and may be any value from 0 to 65535 but is ignored by the DSPEC. Execution Warnings: %000004073<CR> No segment selected (occurs with other warnings).
  • Page 66 %000005074 Acquisition already stopped (no changes made). STOP_OPTIMIZE Stops the optimization in progress. The DSPEC may be in an indeterminate mode. See also START_OPTIMIZE. STOP_PZ_AUTOMATIC Stops the optimization in progress. The DSPEC may be in an indeterminate mode. See also...
  • Page 67 Prepares the serial line for communication with a terminal. In terminal mode, text sent to the DSPEC echoes back to the host and response records sent to the host by the DSPEC are terminated with a carriage return and line feed. This command has no effect when sent via the mailbox.
  • Page 68 ® DSPEC Digital Gamma-Ray Spectrometer Sample Response: DEL_COLL 0000000000001.5 1.5 is a legal setting. Execution Errors: %131128085<CR> The first value is incorrect. %131132080<CR> A value is needed. VERIFY_GAIN_COARSE cg[,inc] Allows exploration of the legal coarse gain settings. It returns the closest legal coarse gain setting to cg.
  • Page 69 8-bit binary checksum of the entire record up to the checksum byte itself. After the DSPEC responds with a binary data record, the host computer must prompt for the next record with one of the following handshake prompts: GO<CR>, RE<CR>, or...
  • Page 70 Digital Gamma-Ray Spectrometer to be sent by the DSPEC or the % response if the last record has already been sent. RE causes the previous binary data record to be resent exactly as it was the last time. HA causes the WRITE command to be halted and responds with a %130131078<CR>...

  • Page 71: Index

    INDEX ADC gate ......35, 48 Automatic PZ ......60 Change Sample .
  • Page 72 ® DSPEC Digital Gamma-Ray Spectrometer...

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