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The Model 3001 NIM MCA is a versatile, low cost, 1024-channel multichannel analyzer offering three analysis modes: charge (area), voltage (peak), and time (start/stop). Each of the 3001s 1024 channels has a count capac ity of 16 bits (65,535). The contents may be displayed in log/linear fashion on any X-Y oscilloscope. The display is active on a time-available basis, thus affording display during data accumulation. A front-panel switch selects intensification of every tenth or fiftieth channel. Data may be accumulated and displayed in selected 256-channel quadrants or in the full 1024-channel memory. In addition to both an internal and external trigger capability with variable gate width, the 3001 provides external gate and inhibit inputs, which are also used as start and stop inputs in the time mode.

Rear-panel digital outputs are supplied to allow for data transfer to interface options including the CAMAC Dataway (IEEE-583). The output connector may also be used to load or increment any one of the 16-bit word in memory. This feature allows the 3001 to be used as an additional 1024 words of memory and to act as a histo gram display module.

The 10-bit ADC used for the Q (charge) mode has a sensitivity of 0.25 pC/channel, directly compatible with photomultiplier anodes pulses, thus eliminating the need for a charge-sensitive preamplifier. In the Q mode, the input current is integrated for a duration ranging from 20 nsec to 1 µsec. A front-panel adjustable internal gate is generated by either an internal or an external trigger, or an external gate pulse may be directly applied to the MCA. Operating in the Internal mode, the Model 3001 is a stand-alone device, possessing an internal discrimina tor of 1 mV minimum threshold. The Q input is terminated in 50 ohm and all analog circuitry is DC-coupled, thus eliminating the need for DC restoration instrumentation.

The 10-bit TDC used for the T (time) mode of the Model 3001 digitizes time intervals by the start-stop technique and stores their spectra. Full-scale time intervals are 102 nsec and 1024 nsec, offering respective resolutions of 100 psec/channel and 1 nsec/channel. The start and stop inputs are leading edge triggered, responding to fast NIM (negative) signals. Uses of the T mode include time-of-flight, counter timing, delay measurement, b-V time correlation spectra, and drift chamber calibration.

In the V (voltage) mode, the output of any voltage source, e.g., a charge-sensitive preamplifier, may be analyzed. The maximum (peak) voltage (of signals > 50 nsec rise time) applied to the input during the gating interval is digitized, thus making external stretching circuits unnecessary. The full-scale input in the V mode is +1 V (+10 V is switch selectable), offering a resolution of 1 mV (10 mV) consistent with that of a Si(Li) detector. The internal gate may be extended to 5 µsec in this mode.

The CAMAC Model 2301 qVt Interface has been designed to allow spectrum transfer to computer or to allow data transfer to the Model 3001 Multichannel Analyzer for display or histogramming. The 2301 allows the qVt to be used for calibration and setup as well as for display during the operation of an experiment.

The 3001 can be connected directly to an IBM compatible computer by using the model 3031 QVT interface and Model 1691B interface card. These units are described on separate data sheets.

The 3001 may be used to set gain and timing of hodoscope or calorimeter elements. When the first order high voltage and cable delay parameters are set, the information may be transferred to the computer for straightfor ward analysis before the systems software is fully operational. In this way, an array of gains and timing parame ters may be evaluated for second order corrections. Just as in many commonly used minicomputers, data in the 3001 is organized into 16-bit words. The 2301 allows this memory to be written into from the CAMAC Dataway. The data loaded into memory is then automatically displayed without the need for expensive storage display or the requisite CPU time required to refresh a standard CRT.

An increment feature allows any channel of the 3001 to be incremented by 1. This feature allows use of the analyzer as a histogram and display module without significant core usage for data storage or software. Since the display is continuously active, the experimenter may watch the spectrum accumulate without significant CPU overhead.

The Model 2301 contains an Incrementing Address Register which may be loaded from the CAMAC Dataway. The value contained in the register is used to address memory for both read and write operations. After the read or write operation is performed, the register is incremented by 1. Using this scheme, data may be transferred to or from the qVt memory at the rate of 1 word per CAMAC cycle.


For direct digitizing of photo-multiplier anode current pulses. No-charge sensitive preamp is required, permitting high counting rates and pile-up elimination.


For use as a conventional Pulse Height Analyzer. Accepts positive voltage signals or dc levels.


For Start-Stop timing measurements. Not multi-scaling. No TAC necessary.


Model 3001 qVt Multichannel Analyzer


Analysis Modes:
Q: Current integrating (charge sensitive); integration interval 20 nsec to 1 µsec; full scale, 256 pC ±10% sensitivity, .25 pC/channel. V: Peak voltage; input signal rise time, 50 nsec; full scale, +1 V or +10 V ±10%; resolution, 1 mV or 10 mV/channel; external gate width, 100 nsec minimum to 1 µsec or switch selectable 5 µsec maximum. T: Time interval (Start/Stop); full scale internally switch selectable, 102 or 1024 nsec ±10%; resolution, 100 psec and 1 nsec respectively.

Number of Channels: 1024 (10-bits); 256 (8-bits) in quadrants; overflow counts are stored in the last address of the selected memory segment.

Memory Size: 16 bit - 1 per channel (65,535 counts).

Digitizing Time: 12 µsec +0.05 µsec/channel.

Temperature Stability: ±.03% of full scale/°C.

Long Term Stability: ±0.2% of full scale/week, maximum.

Integral Non-linearity: 0.25% of reading 2 channels.

Display: 100/sweeps/second.

Channel Intensification: Every 10th or 50th channel, front-panel selectable.


#2 width, RF-shielded NIM-standard module, conforming to specifications outlined in AEC Report TID-20893.

Voltages Used: ±24 V, ±12 V. (Note: a rear-panel switch permits operation from ±6 V (if available) instead of ±12 V.)

Current Requirements: For ±6 V operation; 260 mA at +24 V, 500 mA at -24 V, 150 mA at +12 V, 150 mA at -12 V, 2200 mA at +6 V, 510 mA at -6 V. (Note ±6 V requirements add to the ±12 V requirements listed above if the ±6 V option is not used.)

Front-Panel Connectors: BNC.


Analog Input (Q and V Modes):
Direct-coupled; 50 ohm impedance, 93 ohm option in V mode; protected to ±100 V for 1 µsec; linear range, 0 to -1 V in Q mode, 0 to +10 V in V mode.

External Gate/External Trigger/Start/Internal Gate View: One common front-panel connector; functionally controlled by trigger mode switch; requires -600 mV signal into 50 ohm.

Q and V Modes: In External Gate (EXT. GATE) mode, the gate width is equal to the duration of the gate pulse applied to this connector. In External Trigger mode (EXT. TRIG), the internal gate is triggered by the leading edge of a fast NIM signal applied to this connector (minimum trigger width, 10 nsec). In Internal (INT) mode, the inter nally-generated gate may be viewed at this connector. Amplitude ~ 100 mV.

Q Mode: Usable gate duration, 20 nsec to 1 µsec.

V Mode: Minimum duration, 100 nsec. Maximum duration, 5 µsec (gate must enclose peak of input signal to be measured).

T Mode: The leading edge of Start input begins the start-stop time measurement; minimum pulse width, 10 nsec.


Operating Mode: One of the three analysis modes (Q, V, or T) is selected by a 3-position switch.

Trigger Mode: A 3-position switch selects internal trigger operation (INT), External Trigger operation (EXT TRIG), or operation via an externally-applied gate pulse (EXT GATE).

Continuous/Stop at Overflow: A 2-position switch either permits continuous data collection and display or limits each channel to a full scale capacity.

Intensify: Either every 10th or 50th channel is intensified on the display, determined by a front-panel 2-position switch.

Display LIN/LOG: Selects linear or logarithmic display.

Start/Stop: Front-panel, two-position, spring-return toggle clears all memory and register. Start/Stop switch must be simultaneously placed in stop position.

Memory Select (Full-1/4-2/4-3/4-4/4): In the Full position, all 1024 channels accept and display input data. In the 1 /4 position, the first quadrant (256 channels) accepts and displays input data. Full-scale range settings remain the same (i.e., 256 pC, +1 V, and 102 or 1024 nsec); similar for 2/4, 3/4, 4/4.

Vertical Gain: In LIN (linear) mode, an 8-position switch selects a maximum number of counts to be displayed per channel, between 512 and 65K.


Q Input:
Analog input; 50 ohm impedance; DC-coupled. Accepts input charge of 0 to 256 pC. Protected to ±100 V.

V Input: Analog input 50 ohm impedance (93 ohm optional). Accepts input voltage of 0 to +1 V (with switch selec tion 0 to 10 V range). Protected to ±100 V.

Gate Input/Output: Multifunctional connector. Acts as trigger or gate input/output in Q or V mode. Acts as start input in T mode. Input impedance 50 ohm. Accepts NIM fast signals. (See detailed specifications.)

Inhibit/Stop: Accepts fast NIM signals. Acts as inhibit in Q or V mode & stop input in T mode. Impedance 50 ohm.


Threshold Test Point:
Reads 1000X preset threshold value in Internal mode operation.

Internal Gate View: Internally generated gate is available for oscilloscope monitoring on the Gate Connector when Internal Trigger is selected. Amplitude: -100 mV.

Internal Gate Test Point: Internally generated is available for oscilloscope monitoring when the Internal or External Trigger mode is selected. Amplitude, -200 mV.

Busy: TTL low level output during conversion time.

Horizontal Out: Horizontal deflection voltage for CRT proportional to channel number; 0-5 volts for full or quadrant display. Minimum load impedance 1 kohm.

Vertical Out: Vertical deflection voltage for CRT proportional to number of counts. Linearity ±0.2% of full scale. Full -scale output of 5 V corresponds to 200 db/V in the log mode. Minimum load impedance 1 kohm.


Connector Type:
44-contact card-edge connector; TTL levels.


Memory Overflow (22)
External Enable (4)
External Memory Address Latch (R)
Memory Enable (21)
External Load (N)
External Read/Write (M)
Incrementing Register (P)
16 Data bits (6-20)

Model 2301 Interface for qVt Multichannel Analyzer

Inputs and Outputs:
44 on a single front-panel edge connector. Pin-for-pin identical to the qVt rear I/O connector.

LAM Button: A front-panel push-button sets the L level to true. Intended to allow a manual interrupt.

Packaging: In conformance with CAMAC standard for nuclear modules (ESONE Committee Report EUR4100e). RF shielded CAMAC #1 module.

Current Requirements: 500 mA at +6 V.


Model 2301: QVT CAMAC Interface

Model 3001: QVT MCA

Model 3031: QVT NIM Interface

Model 1691B: PC Interface Card (for 3031)


Model 2301


A Q = 1 response is generated in recognition of an F(2), F(16), F(17), or F(25) command only if a valid address (0 to 1023) is contained in the Internal Address Register. A Q = 0 response applied for all other function codes.

X: An X = 1 (Command Accepted) is generated when a valid F and N is received.

L: An L = 1 Look-At-Me signal is generated by pressing the front-panel LAM Button. The condition persists until an F(2) is received.


Read qVt data from the channel whose address is in the Incrementing Address Register to Dataway lines R1 to R16. Advances the Incrementing Address Register by one.

F(9): Clear qVt. Clears all 1024 memory locations.

F(16): Write into qVt memory channel whose address is in the Incrementing Address Register. Ad vances the Incrementing Address Register by one.

F(17): Write into Incrementing Address Register. The data contained on the Dataway lines W1 to W10 are written into the Incrementing Address Register.

F(24): Stop qVt. Issues a STOP command to the qVt.

F(25): Increment qVt. The data in the address contained in the Incrementing Address Register is incremented by 1.

F(26): Start qVt. Issues a START command to the qVt.

Copyright© September 1995. LeCroy is a registered trademark of LeCroy Corporation. All rights reserved. Information in this publicaction supersedes all earlier versions.