Applied Physics Systems 851 User manual

DOC PN:260-0922 DOC DESC: Model 851 User Manual SEPTEMBER2022. REVISION: 04
APPLIED PHYSICS SYSTEMS, INC. |APPLIEDPHYSICS.COM
1
MODEL 851
NATURAL GAMMA SENSOR
USER MANUAL
CONTACT US
HEADQUARTERS
425 Clyde Avenue Mountain View, CA 94043
OFFICE
650.965.0500
EMAIL
[email protected]m
APPLIEDPHYSICS.COM

DOC PN:260-0922 DOC DESC: Model 851 User Manual SEPTEMBER2022. REVISION: 04
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COPYRIGHT
Copyright 2014 - 2022 Applied Physics Systems Incorporated.
All Rights Reserved. The contents of this manual may not be reprinted in part or
whole without permission.
The contents of this manual are subject to change without notice.
TRADEMARKS
All other brands or products mentioned are trademarks or registered trademarks
of their respective holders and should be treated as such.
CONTACT INFORMATION
Applied Physics Systems
Corporate Headquarters
425 Clyde Avenue
Mountain View, California 94043 USA
Phone: [phone]
Email: [e-mail]
Web: www.appliedphysics.com
Technical Support Hours:
Monday - Friday
9:00 AM - 5:00 PM
Pacific Standard Time
DOCUMENT NUMBER
260-4709-04-0922

DOC PN:260-0922 DOC DESC: Model 851 User Manual SEPTEMBER2022. REVISION: 04
APPLIED PHYSICS SYSTEMS, INC. |APPLIEDPHYSICS.COM
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REVISION HISTORY
Revision
Description
1
Initial Draft of this manual.
2
Change to power consumption specification
3
Removed reference to section 7.3 spreadsheet to calculate total
gamma correction factor.
4
Reformatted the manual
TABLE OF CONTENTS
.................................................................................................................................................................................................1
MODEL 851.........................................................................................................................................................................1
COPYRIGHT..................................................................................................................................................................... 2
TRADEMARKS................................................................................................................................................................. 2
CONTACT INFORMATION........................................................................................................................................ 2
DOCUMENT NUMBER................................................................................................................................................. 2
REVISION HISTORY...................................................................................................................................................... 3
TABLES ................................................................................................................................................... 4
FIGURES ................................................................................................................................................. 4
1–INTRODUCTION .....................................................................................................................................................5
2-SYSTEM SPECIFICATIONS................................................................................................................................6
3-MECHANICAL FEATURES .................................................................................................................................. 7
4-ELECTRICAL INTERFACE....................................................................................................................................8
5-DATA INTERFACE..................................................................................................................................................9
6-MODEL 851 GAMMA SENSOR COMMANDS ..........................................................................................10
6.1 –MODEL 851 SYSTEM BINARY DATA REQUEST COMMANDS........................................................11
6.1.1 -ID COMMAND (KEYBOARD COMMAND 0, 0X30 HEX)...............................................................12
6.1.2 -BINARY COUNT COMMAND (KEYBOARD COMMAND 1, 0X31 HEX)...................................12
6.1.3 -BINARY RATE COMMAND (KEYBOARD COMMAND 2, 0X32 HEX)......................................13
6.1.4 -BINARY TRANSMISSION DECODING CONVENTION...................................................................14

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6.2 –MODEL 851 SYSTEM ASCII DATA REQUEST COMMANDS ..........................................................15
6.2.1 -ASCII RATE COMMAND (KEYBOARD COMMAND 6, 0X36 HEX)..........................................15
6.2.2 -ASCII ACCELEROMETER COMMAND (KEYBOARD COMMAND 7, 0X37 HEX)..............15
6.2.3 -ASCII SEND 851 CONFIG DATA COMMAND (KEYBOARD COMMAND R, 0X72 HEX)
............................................................................................................................................................................................. 16
6.3 -MODEL 851 CONFIGURATION COMMANDS......................................................................................17
7-CORRECTIONS TO THE GAMMA COUNT RATE FOR USE IN MWD SYSTEMS ........................18
7.1 -PRESSURE BARREL CORRECTION (PB CORRECTION)...................................................................19
7.2 -DRILL COLLAR AND DRILLING FLUID CORRECTION (CM CORRECTION) .......................... 20
8-NET SYSTEMS........................................................................................................................................................22
8.1 -NET PACKET DESCRIPTION.........................................................................................................................23
8.2 -NET PROTOCOL.............................................................................................................................................. 24
8.3 -THE CRC PROGRAM..................................................................................................................................... 25
A-MODEL 851 CONFIGURATION COMMAND REFERENCE................................................................ 28
TABLES
Table 1. Model 851 Gamma Sensor Specifications ............................................................................6
Table 2. Model 851 Electrical Interface.......................................................................................................8
Table 3. Model 851 Data Request Commands.....................................................................................11
Table 4. ID Command Format Example Key.........................................................................................12
Table 5. Binary Count Command Format Example Key...............................................................13
Table 6. Rate Command Format Example Key...................................................................................14
Table 7. Send Model 851 Config Command Format Example Key ....................................... 16
Table 8. Model 851 Configuration Commands ...................................................................................17
Table 9. NET Packet Key......................................................................................................................................23
Table 10. NET Directional Sensor Command Key ............................................................................. 25
Table 11. Model 851 Configuration Commands ................................................................................. 28
FIGURES
Figure 1. Model 851 Sensor with Shock Mount Rings.......................................................................... 7
Figure 2. Model 851 Connectors...................................................................................................................... 7
Figure 3. Pressure Barrel Correction Factors in Inches ..................................................................19
Figure 4. Pressure Barrel Correction Factors in Centimeters .................................................. 20

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1 – INTRODUCTION
The Applied Physics Systems Model 851 Gamma Sensor is designed to measure
the background gamma radiation occurring in well bores. This sensor is used
mainly to detect the presence of porous petroleum reservoirs (such as
sandstones and limestones), which are generally less radioactive than nonporous
strata (such as shales).
The Model 851 gamma sensor can be used as either a standalone system or in
conjunction with Model 850 directional sensors:
• When used as a standalone system, communication with the Model 851
gamma sensor is by means of a bi-directional serial port operating at TTL
logic levels. An ASCII command language is used to send commands to the
Model 851 and data from the Model 851 is sent out in ASCII format.
• When the Model 851 is used in conjunction with a Model 850 directional
sensor, a NET interface is used for communication. For the NET
configuration, data from the Model 851 gamma sensor is continually
requested by the Model 850 directional sensor and is combined with
directional data and transmitted out the Model 850 main serial data
interface.
To achieve high gamma sensitivity, a 0.75-inch diameter by 6-inch long
scintillation crystal is used to detect gamma rays. Scintillation light flashes
caused by individual gammas are amplified by using a photo multiplier tube that
outputs a short pulse for each gamma detected. Pulses are further amplified and
counted by a microprocessor system that also handles communication with
external devices.
The Model 851 system also has two 50-gee vibration sensors (accelerometers),
which can be used to monitor drilling induced vibration and shock. The two
vibration sensors are oriented to measure axial and transverse shock and
vibration.

DOC PN:260-0922 DOC DESC: Model 851 User Manual SEPTEMBER2022. REVISION: 04
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2 - SYSTEM SPECIFICATIONS
This section describes the system specification for the Model 851 Gamma Sensor.
Table 1. Model 851 Gamma Sensor Specifications
Electrical
Input Voltage Range
+15 V to +30 V
Current Draw
90 mA @ 15 V, 45 mA @ 30 V
Power Requirement
1.5 W (max)
Logic Level
TTL
Baud Rate
User Programmable up to 9600 baud
Protocol
User selectable, ASCII or Binary
Environmental Performance
Operating Temperature Range
0°C to 150°C
Storage Temperature Range
-25°C to +175°C
Shock
1000 G1ms half sine wave
Vibration (random)
10 Grms, 50-250Hz
Performance
Accuracy
± 5%
Thin-bed Resolution
6" (236 mm) in an 8” diameter hole
Range
0 - 511 API counts/second (30 second
intervals)
Vibration and Shock Detection
2 axis ± 50 gee 400 Hz
Physical
Outside Diameter (O.D.)
1.0” (26.4 mm)
Length
17.185” (436.5 mm) with standard connectors
Weight
1.1 lbs (499 grams)
Scintillation Crystal
0.750" dia. (19.05 mm) and 6" (152.4 mm) in
length, mounted in
Stainless Steel Case
Photomultiplier Tube
Hamamatsu Model 3991A
Connectors
Main Connector: MDM9PH003P (ITT Cannon)
Mating Connector: MDM9SH003L (ITT Cannon)

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3 - MECHANICAL FEATURES
A drawing of the Model 851 Sensor is shown in Figure 1. When used in pulser or EM
MWD systems, usually the Model 851 is mechanically connected directly to a
Model 850 directional sensor and mounted in a cylindrical pressure barrel. An
overlap mechanical connection using four 8-32 stainless steel screws is used to
attach the Model 851 to the Model 850 directional sensor.
When the Model 851 is mechanically mated to the Model 850 system, electrical
connection is also made via a 9-pin MDM connector mounted in the overlap
recess. This connector is float-mounted to reduce vibration-induced damage
that can occur in drilling applications.
Figure 1. Model 851 Sensor with Shock Mount Rings
Figure 2. Model 851 Connectors

DOC PN:260-0922 DOC DESC: Model 851 User Manual SEPTEMBER2022. REVISION: 04
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4 - ELECTRICAL INTERFACE
The electrical connections for the Model 851 Gamma Sensor are shown in Table 2.
Table 2. Model 851 Electrical Interface
MDM Pin
Function
1
Serial (TTL level) from gamma
2
Serial (TTL level) to gamma
3
Voltage
4
Ground
Remaining pins
Not used
Communication with the Model 851 is accomplished via the TTL-level serial
communications lines shown in Table 2. The Model 851 can be connected to a PC
for testing if a TTL-to-RS232 conversion box is inserted in the communication lines
between the Model 851 and PC.
TTL-to-RS232 conversion systems can be supplied by Applied Physics Systems or
other vendors.

DOC PN:260-0922 DOC DESC: Model 851 User Manual SEPTEMBER2022. REVISION: 04
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5 - DATA INTERFACE
Commands are sent to the Model 851 as ASCII characters at the default baud rate
of 9600 using 8-bit data words with one stop bit and no parity bit.
An easy method of communicating with the Model 851 is to use a PC running a
terminal emulator program such as Windows HyperTerminal or ProComm. When
these programs are used, any typed commands are sent out the specified COM
port and any data received from the 851 system are displayed on the PC display
device.
When using a terminal emulator, the emulator program must be configured for
direct connect to a COM port on the PC and the following settings should be used:
• baud rate = 9600
• data word = 8-bits
• no parity
• stop bits = 1
• handshaking option = none
All commands to the Model 851 are invoked by multi byte sequences in which the
first byte is always a command token hex 06 (0x06). The bytes following the token
define the command being sent. Commands sent to the 851 system are of two
general types:
• Binary and ASCII data requests
• System configuration commands
ASCII data transmitted from the 851 sensor is formatted to be easily displayed on
a computer monitor. Binary data is transmitted from the 851 sensor in a data
packet with the following structure:
<Token> <Command> <data1> <data2>…<dataN> <CRCL> <CRCH> <token> <Eot>
Where:
• <Token> = 0x06,

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• <CRCL> <CRCH> is a two byte CRC, and
• <EOT> = (0x06)(0x04) and denotes the end of the packet.
If the token occurs within the requested data sequence it is replaced with two
tokens.
Multi-byte binary numbers in the requested data sequence are returned highest
byte first, then next highest, with the least significant byte last. To send the
command token using a computer keyboard hold down the control key and type
the letter f.
The gamma sensor includes two accelerometers one which measures transverse
and one which measure axial shock. Both accelerometers have a full scale equal
to ±50g. The reported data from the accelerometers is calibrated to read in gees.
The Model 851 system also has a temperature sensor. Data reported from the
temperature sensor is calibrated to read in degrees centigrade.
6 - MODEL 851 GAMMA SENSOR
COMMANDS
This section describes the two types of Model 851 gamma sensor commands:
• Binary data request commands
• ASCII data request commands
• Configuration commands
To send a data request command to the 851 system, enter the command token
<Ctrl/F>
(pressing the Ctrl key and the f key simultaneously) followed by one of the
keyboard commands listed in Table 3. Press Enter to send the command.
The data request commands are listed in the table below: