Measurements of total and partial charge-changing cross sections for 200- to 400-MeV/nucleon ${}^{12}\mathrm{C}$ on water and polycarbonate

We have studied charged nuclear fragments produced by 200- to 400-MeV/nucleon carbon ions, interacting with water and polycarbonate, using a newly developed emulsion detector. Total and partial charge-changing cross sections for the production of B, Be, and Li fragments were measured and compared with both previously published measurements and model predictions. This study is of importance for validating and improving carbon-ion therapy treatment planning systems and for estimating the radiological risks for personnel on space missions, because carbon is a significant component of galactic cosmic rays.

Figure 1

(a) A schematic view of the whole structure of the Emulsion Cloud Chamber (ECC). It has 65 layers of emulsion modules and water targets. (b) Detailed structure of the ECC. An emulsion module consists of four emulsion sheets and a polycarbonate plate. (c) Cross section of an OPERA film. An OPERA film has emulsion layers coated on both sides of a TAC base.

Figure 2

Distribution of the pulse heights in sheets A for secondary tracks. The tracks with pulse heights less than 210 are discriminated as single-charged tracks.

Figure 3

A scatter plot between averaged pulse heights in sheets B and sheets D for secondary tracks. One can see clear discrimination of track charges from $Z=2$ to $Z=6$.

Figure 4

An example of a charge-changing track. Open circles (black squares) represent averaged pulse heights in sheets B (sheets D). We traced pulse height variations along primary carbon tracks. In this case, a carbon beam changes into a beryllium between 24th and 25th modules.

Figure 5

Distribution of local distance between the surface of each module and reconstructed vertices. The target materials of interactions were identified according to the detector structure [also see Fig. 1b].

Figure 6

Total charge-changing cross sections of carbon-water interactions in comparison with previous measurements and a model calculation. The vertical error bars indicate statistical errors only in this and the followings figures.

Figure 7

Total charge-changing cross sections of carbon-polycarbonate interactions in comparison with previous measurements and a model calculation.

Figure 8

Partial charge-changing cross sections of carbon-water interactions of $\Delta Z=1$ in comparison with previous measurements and a model calculation.

Figure 9

Partial charge-changing cross sections of carbon-water interactions of $\Delta Z=2$ in comparison with previous measurements and a model calculation.

Figure 10

Partial charge-changing cross sections of carbon-water interactions of $\Delta Z=3$ in comparison with a model calculation.

Figure 11

Partial charge-changing cross sections of carbon-polycarbonate interactions of $\Delta Z=1$ in comparison with previous measurements and a model calculation.

Figure 12

Partial charge-changing cross sections of carbon-polycarbonate interactions of $\Delta Z=2$ in comparison with previous measurements and a model calculation.

Figure 13

Partial charge-changing cross sections of carbon-polycarbonate interactions of $\Delta Z=3$ in comparison with a model calculation.