What is claimed is:1. A heat treatment apparatus comprising:a processing container extended in a vertical direction;a heater provided around the processing container;a temperature sensor provided along a longitudinal direction of the processing container either in the processing container or in a space between the processing container and the heater; anda pair of first partitions provided in the space facing each other across a half line that extends from a central axis of the processing container and passes through the temperature sensor, and extending along the longitudinal direction of the processing container,wherein the heater includes:a heat insulator that covers an outer circumference of the processing container,a heater element provided inside the heat insulator, anda holder that is attached to an inner surface of the heat insulator and holds the heater element, andwherein one of the first partitions is detachably attached to the heater element or the holder.2. The heat treatment apparatus according to claim 1, wherein the temperature sensor includes a plurality of temperature gauges along the longitudinal direction of the processing container, andan upper end of one of the first partitions is positioned above an uppermost temperature gauge among the plurality of temperature gauges.3. The heat treatment apparatus according to claim 1, wherein each of the first partitions is divided into a plurality of portions.4. The heat treatment apparatus according to claim 1, wherein each of the first partitions is provided with a gap with respect to an outer surface of the processing container.5. The heat treatment apparatus according to claim 1, wherein each of the first partitions is made of a ceramic material.6. The heat treatment apparatus according to claim 1, further comprising:a second partition provided in the space and extending along a circumferential direction of the processing container.7. The heat treatment apparatus according to claim 6, wherein the second partition includes a circular arc plate-like portion equal to or larger than a semicircle and extending along the circumferential direction of the processing container from one of the first partitions to a remaining one of the first partitions.8. The heat treatment apparatus according to claim 7, wherein the second partition includes a circular arc plate-like portion smaller than a semicircle and extending along the circumferential direction of the processing container from one of the first partitions to a remaining one of the first partitions.9. The heat treatment apparatus according to claim 6, further comprising:one or a plurality of third partitions provided on the same circumference as the pair of first partitions at an interval from the pair of first partitions, and extending along the longitudinal direction of the processing container,wherein the second partition includes a plurality of circular arc plate-like portions extending along the circumferential direction of the processing container to connect the pair of first partitions and the third partition.10. The heat treatment apparatus according to claim 6, wherein the heater is divided into a plurality of heating areas that are individually controllable in the longitudinal direction of the processing container, andthe second partition is provided at or in the vicinity of a boundary between a lowermost heating area among the plurality of heating areas and a heating area adjacent above the lowermost heating area.11. The heat treatment apparatus according to claim 6, wherein the heater is divided into a plurality of heating areas that are individually controllable in the longitudinal direction of the processing container, anda plurality of second partitions is provided corresponding to each boundary of the plurality of heating areas or to the vicinity of the boundary.12. The heat treatment apparatus according to claim 6, wherein the second partition is divided into a plurality of portions.13. The heat treatment apparatus according to claim 6, wherein the heater includes:a heat insulator that covers an outer circumference of the processing container;a sub-heater provided inside the heat insulator; anda holder that is attached to an inner surface of the heat insulator and holds the sub-heater, andthe second partition is detachably attached to the sub-heater or the holder.14. The heat treatment apparatus according to claim 6, wherein the second partition is provided with a gap with respect to an outer surface of the processing container.15. The heat treatment apparatus according to claim 6, wherein the second partition is made of a ceramic material.