PA-1000 Environmental Radiation Monitor Radi


Every day, wherever we go, we are exposed to minute amounts of environmental radiation.* This environmental radiation is emitted continuously, day and night, from various objects and substances in the natural world and our living environment.

Most environmental radiation consists of three types: alpha rays (α), beta rays (β) and gamma rays (γ).  HORIBA's PA-1000 "Radi" environmental radiation monitor makes it easy for non-specialists to measure even minute levels of gamma rays.

* Environmental radiation, also known as natural radiation, includes radiation emitted from space, soil, stones, the ground and the air, as well as from manmade objects such as concrete and buildings



  • Easy measurement by Anyone, Anytime, Anywhere

  • Designed with plant-based plastic material helping to reduce petroleum consumption

  • High performance detection with a CsI (Tl) scintillator
    The Radi can measure radiation levels ranging from normal natural radiation to levels 100 to 200  times that intensity. Even non-specialists will find it easy to measure radiation of 0.001 - 9.999 µSv/h.

  • Splash-resistant construction
    The Radi can be used with confidence even if there are water droplets on the surface.  (JIS water resistance protection grade IPX4)

  • Compact and lightweight (175 g / 6.2 oz)

  • Uses two AA batteries.
    Battery life 50 hours or more (when manganese dry cell batteries are used)

Manufactured by HORIBA


Detection method


Type of radiation measured

Gamma rays (γ)


Min. 1000 counts per minute (1000 cpm)

for 1 µSv/h

Relative error of indication


Indicator value variation

Max. 0.1 coefficient of variation

Energy range

More than 150 keV

Energy properties

0.5 - 3* (150 keV - 1250 keV)

Effective measurement range and display

0.001 - 9.999 µSv/h

4-digit digital display

(count value converted into µSv/h)

Sampling time

60 seconds

Display interval

60-second integrated value (moving average) displayed every 10 seconds

External dimensions

68 (W) × 28 (D) × 121 (H) mm

[ Inch size : 2.7 (W) × 1.1 (D) × 4.8 (H) ]

Weight (without batteries)

Max. 175 g (6.2 oz)


Instruction manual, two AA dry cell batteries, neck strap

* Relative sensitivity with 1 as the sensitivity to cesium 137 (137Cs) (662 keV).

Note: This unit is designed only to measure the quantity of radiation at the measurement location. It does not determine the safety or danger posed by that quantity of radiation.




Types of radiation

  • Alpha rays (α): Alpha rays are streams of positively charged particles made up of two neutrons and two protons (helium nucleus). In the natural world, alpha rays are given off by radium 226. In air, the particles cannot travel more than a few centimeters.
  • Beta rays (β): Beta rays are streams of electrons. In air, the particles can travel several dozen centimeters in a zigzag pattern.
  • Gamma rays (γ): Gamma rays, the most penetrating type of radiation, are electromagnetic waves. They can pass through the human body. X-rays that are used in X-ray machines are also electromagnetic waves.

Radiation units

  • Becquerel (Bq): The becquerel (Bq) is the unit of radioactivity. The radioactivity of a substance measured in becquerels is the number of its nuclei that decay each second.
  • Gray (Gy) and Sievert (Sv): These units express the effect of radiation. The gray expresses the amount of radioactive energy received, while the sievert expresses the effect on a human being. Normally the gray and the sievert are used to express quantities per hour; the units are Gy/h and Sv/h, respectively.