Ludlum Measurements 44-157 User manual

LUDLUM MODEL 44-157 &
44-159 & 44-159-1 & 44-162
GAMMA PIPE MONITORS
September 2016

LUDLUM MODEL 44-157 &
44-159 & 44-159-1 & 44-162
GAMMA PIPE MONITORS
September 2016

STATEMENT OF WARRANTY
Ludlum Measurements, Inc. warrants the products covered in this manual to be free of
defects due to workmanship, material, and design for a period of twelve months from the
date of delivery. The calibration of a product is warranted to be within its specified
accuracy limits at the time of shipment. In the event of instrument failure, notify Ludlum
Measurements to determine if repair, recalibration, or replacement is required.
This warranty excludes the replacement of photomultiplier tubes, G-M and proportional
tubes, and scintillation crystals which are broken due to excessive physical abuse or used
for purposes other than intended.
There are no warranties, express or implied, including without limitation any implied
warranty of merchantability or fitness, which extend beyond the description of the face
there of. If the product does not perform as warranted herein, purchaser’s sole remedy
shall be repair or replacement, at the option of Ludlum Measurements. In no event will
Ludlum Measurements be liable for damages, lost revenue, lost wages, or any other
incidental or consequential damages, arising from the purchase, use, or inability to use
product.
RETURN OF GOODS TO MANUFACTURER
If equipment needs to be returned to Ludlum Measurements, Inc. for repair or calibration, please send to
the address below. All shipments should include documentation containing return shipping address,
customer name, telephone number, description of service requested, and all other necessary information.
Your cooperation will expedite the return of your equipment.
LUDLUM MEASUREMENTS, INC.
ATTN: REPAIR DEPARTMENT
501 OAK STREET
SWEETWATER, TX 79556
800-622-0828 325-235-5494
FAX [phone]

Ludlum Measurements, Inc. September 2016
Table of Contents
Introduction 1
Unpacking and Repacking 2
Specifications 3
Operating Procedures 6
Safety Considerations 6
Parts Lists, Drawings, and Diagrams 7
Energy Response Curves 19

Model 44-157, 44-159, 44-159-1, 44-162
Gamma Pipe Monitors
Ludlum Measurements, Inc. Page 1 September 2016
Introduction
The series of scintillator gamma pipe monitors (Models 44-157,
44-159, 44-159-1 and 44-162) is primarily used for detecting low
levels of gamma radiation in the range of 60 keV–1.25 MeV.
The Model 44-157 consists of a 2 x 2 inch NaI crystal coupled
to a photomultiplier tube housed in aluminum. The Model 44-
159 and 44-159-1 consist of an 18 x 18 mm CsI crystal, and the
Model 44-162, a 3 x 3 inch NaI crystal, both also coupled to a
photomultiplier tube housed in aluminum.
The detector is energy dependent, typically over-responding in
the 100 keV range and under-responding above 1 MeV when
normalized to 137Cs.
The gamma pipe monitors will operate with any Ludlum
instruments or equivalent instruments that provide 700–1200
volts. The recommended instrument input sensitivity is
approximately 10 mV or higher.
Some common applications for this detector include
background radiation monitoring, low-level radiation detection,
and spectrum analysis when used in conjunction with a single-
or multi-channel analyzer.
Model 44-159-1

Model 44-157, 44-159, 44-159-1, 44-162
Gamma Pipe Monitors
Ludlum Measurements, Inc. Page 2 September 2016
Note:
If the detector is used in a manner not intended by the
manufacturer, the detector may not function properly.
Note:
The detector does not contain any consumable materials.
Unpacking and Repacking
Remove the calibration certificate or detector functional check
certificate and place it in a secure location. Remove the
detector(s) and accessories (if applicable) and ensure that all
items listed on the packing list are in the carton. If multiple
detectors are included, refer to the calibration certificates for
serial number (SN) matches.
To return an instrument or detector for repair or calibration,
provide sufficient packing material to prevent damage during
shipment, and affix appropriate warning labels to promote
careful handling.
Every returned instrument must be accompanied by an
Instrument Return Form, which can be downloaded from
the Ludlum website at www.ludlums.com. Find the form by
clicking the “Support” tab and selecting “Repair and
Calibration” from the drop-down menu. Then choose the
appropriate Repair and Calibration division where you will find
a link to the form.

Model 44-157, 44-159, 44-159-1, 44-162
Gamma Pipe Monitors
Ludlum Measurements, Inc. Page 3 September 2016
Specifications
Scintillator: 44-157: 5.1 x 5.1 cm (2 x 2 in.) (Dia x thickness),
NaI (Tl) crystal
44-159 & 44-159-1: 18 x 18 mm (0.7 x 0.7 in.) CsI
(Tl) crystal
44-162: 7.6 x 7.6 cm (3 x 3 in.) NaI (Tl) crystal
Compatible Instruments: general-purpose survey meters,
ratemeters and scalers
Sensitivity: 44-157: 900 cpm/µR/hr (137Cs gamma)
44-159 & 44-159-1: 120 cpm/µR/hr
44-162: 2300 cpm/µR/hr
Energy Range: 44-157: 60 keV to 3 MeV
44-159 & 44-159-1: 50 keV to 3 MeV
44-162: 60 keV to 3 MeV
Background: 44:157: 9750 cpm
44-159 & 44-159-1: 750 cpm
44-162: 2200 cpm
Operating Voltage: 44-157: 500-1200 Vdc
44-159 & 44-159-1: 700-1200 Vdc
44-162: 500-1200 Vdc
Dynode String Resistance: 44-157: 60 megohm
44-159 & 44-159-1: 100 megohm
44-162: 60 megohm
Efficiency: 44-157: 57Co is 11%; 137Cs is 5%; and 60Co is 10%
44-159 & 44-159-1: 57Co is 14%; 137Cs is 3%; and
60Co is 5%
44-162: 125I is 29%

Model 44-157, 44-159, 44-159-1, 44-162
Gamma Pipe Monitors
Ludlum Measurements, Inc. Page 4 September 2016
Connector: BNC (others available)
Tube: magnetically shielded photomultiplier
44-157 diameter: 16 mm (0.63 in.)
44-159 & 44-159-1 diameter: 16 mm (0.63 in.)
44-162 diameter: 2.9 cm (1.3 in.)
Construction: aluminum housing with beige powder-coat
finish
Temperature Range: -20 to 50 °C (-4 to 122 °F); may be
certified for -40 to 65 °C (-40 to 150 °F)
Size:
44-157: 8.9 x 15.5 cm (3.5 x 6.1 in.) (Dia x L)
44-159: 2.5 x 7.1 cm (1 x 2.8 in.) (Dia x L)
44-159-1: 2.2 x 8.1 cm (0.875 x 3.2 in.) (Dia x L)
44-162: 19.1 x 24.1 cm (7.5 x 9.5 in.) (Dia x L)
Weight:
44-157: 1.4 kg (3 lb)
44-159: 0.1 kg (0.3 lb)
44-159-1: 0.1 kg (0.3 lb)
44-162: 2.3 kg (5 lb)