A survey meter according to the present invention is a portable radiation measurement device. The survey meter comprises a tip portion, an intermediate portion, and a grip portion. A display unit is provided on the top surface of the intermediate portion. The tip portion extends to the intermediate portion with a bent portion therebetween. The tip portion forms an inclined portion. The grip portion has a constricted portion. A radiation detection unit is provided inside the tip portion and is formed by a plurality of sensors arranged in the right-left direction.
1. A survey meter comprising:
an intermediate portion which has a shape extended in a front-back direction and a right-left direction and a display section provided on a top surface thereof;
a tip portion which has a shape extended in the right-left direction, connects to a front side of the intermediate portion via a bent portion, and contains a radiation detection section; and
a grip portion which has a flat shape extended in the front-back direction and the right-left direction and connects to a rear side of the intermediate portion, wherein
the tip portion is rearwardly inclined from the bent portion toward a bottom surface side of said intermediate portion,
the tip portion is rigidly and non-movably fixed to said intermediate portion via said bent portion with said bent portion rigidly maintaining a constant rearwardly inclined angle between said tip portion and said intermediate portion,
the grip portion is rigidly and non-movably fixed to said intermediate portion,
the intermediate portion has a virtual first central axis passing through the intermediate portion in the front-back direction;
the tip portion has a virtual second central axis that is identical to a main measurement direction;
the first central axis and the second central axis intersect in the bent portion; and
an intersection angle between the first central axis and the second central axis defines said rearwardly inclined angle and is set at a non-movable fixed angle that is within a range of 15 to 45 degrees.
2. The survey meter according to claim 1 , wherein:
the intermediate portion and the grip portion are integrally connected, and the intermediate portion and the tip portion are integrally connected;
the intermediate portion and the grip portion have substantially a same thickness and form a flat plate shape as a whole; and
the tip portion has a shape extended in the second central axis direction and the right-left direction and has a tip end surface that is orthogonal to the second central axis.
3. The survey meter according to claim 2 , wherein
the grip portion has a constricted shape when seen from above.
4. The survey meter according to claim 2 , wherein
the tip portion has a tapered shape when seen from above.
5. The survey meter according to claim 1 , wherein
the grip portion has an operation section on a top surface thereof.
6. The survey meter according to claim 1 , wherein:
the radiation detection section includes a plurality of sensors arranged in the right-left direction.
7. The survey meter according to claim 6 , wherein
the radiation detection section includes a filter member which wraps the plurality of sensors.
8. The survey meter according to claim 7 , wherein
said filter member which wraps the plurality of sensors is constructed to improve energy sensitivity and said filter member covers a front surface of said plurality of sensors to a main measurement direction and four side surfaces around said plurality of sensors adjacent said front surface.
9. The survey meter according to claim 8 , wherein said filter is made with copper.
10. The survey meter according to claim 6 , wherein:
each of the sensors is a flat plate semiconductor sensor having a sensitive surface; and
when a main measurement direction is defined as a direction which is orthogonal to the right-left direction and to which the tip portion is directed, and when a tip portion thickness direction is defined as a direction which is orthogonal to the right-left direction and the main measurement direction, the sensitive surface of each sensor is directed to the right-left direction or the tip portion thickness direction.
11. The survey meter according to claim 10 , wherein
the plurality of sensors are layered in the right-left direction.
12. The survey meter according to claim 10 , wherein
the plurality of sensors are arranged in the right-left direction such that the sensitive surfaces thereof are directed to the tip portion thickness direction.
13. The survey meter according to claim 6 , wherein:
said plurality of sensors arranged in the right-left direction include a plurality of flat plate detectors stacked side-by-side in a right-left direction.
14. The survey meter according to claim 1 , wherein
there is provided a control section which selects, from a plurality of sensors, one or more sensors which are caused to perform detection operation according to an amount of radiation.
15. The survey meter according to claim 14 , wherein
the control section changes the number of sensors caused to perform detection operation according the amount of the radiation.