1. Study of the fragmentation of Carbon ions for medical applications Protons (hadrons in general) especially suitable for deep-sited tumors (brain, neck base, prostate) and fat people Giovanni De Lellis Napoli University

2. Dose modulation From the overlap of close peaks (close energies), a conformational profile is obtained The patient is rotated so to avoid a long exposure time of the healthy tissues Size of the sick part

3. Carbon beam Same energy deposit profile as protons but with larger energy loss per unit length one ionization every ~ 10nm (DNA helix ~ 2nm)

4. Charge and mass measurement Density of energy along the track path  Z 2 Multiple scattering or magnetic field provides either p  or p From the combined measurement, we can get p and the mass  A,Z Open issues Knowledge of the Carbon cross-section with human tissues In particular the exclusive cross-section in the different channels so to predict the detailed irradiation of the neighboring tissues  optimization of the therapy with higher effectiveness

5. Facilities in Europe Typically joint beam (physicists) and therapeutic (biological, medical) facilities. In Europe, a high energy (few hundred MeV/nucleon) carbon beam is at GSI, Darmstadt, Germany In Italy (Pavia, close to Milan) the CNAO under construction, starting on 2009 Proton centers more numerous In Italy (linked with INFN) one proton center operative in Catania, Sicily

6. Exposure of an ECC to 400 Mev/u Carbon ions ECC structure: 219 OPERA-like emulsions and 219 Lexan sheets 1 mm thick (73 consecutive “cells”) exposed to 400 Mev/u Carbon ions Lexan:  = 1.15 g/cm 3 and electron density = 3.6 x 10 23 /cm3 e.g. Water 3.3 x 10 23 /cm3 Cell structure LEXAN R0R1R2 R0: sheet normally developed after the exposure R1: sheet refreshed after the exposure (3 days, 30 0 C, 98% R.H.) R2: sheet refreshed after the exposure (3 days, 38 0 C, 98% R.H.)

7. Carbon exposure at HIMAC (NIRS-Chiba)

8. C ions angular spectrum Slope X Slope Y slope X (3  ) slope Y (3  ) P1 -0.150 ±0.004 -0.003 ±0.005 P2 -0.017 ±0.004 -0.002 ±0.005 P3 0.134 ±0.004 -0.001 ±0.005 3.4 cm 2 scanning in each sheet (all sheets scanned)

9. Vertex reconstruction About 2300 vertices analyzed C 3 cm

10. Impact parameter distribution Hydrogen tracks Helium tracks µm

11. Track volume: sum of the areas of the clusters belonging to the track BG, mip Z > 1 p Upstream sheet Downstream sheet (about 5 cm) p  Z > 2 one sheet – R0 type one sheet – R1 type Downstream sheet (about 5 cm) Upstream sheet

12. R0 vs R1 and R1 vs R2 scatter plot H He

13. Charge identification Z = 2 Z = 3 Z = 4 5 R1 VS 5 R2 (2 cm)10 R1 VS 10 R2 (4 cm) 15 R1 VS 15 R2 (6 cm) 20 R1 VS 20 R2 (8 cm) Z = 4 Z = 3 Z = 2 Z = 5 Z = 6

14. Charge separation Journal of Instrumentation 2 (2007) P06004

15. Charge distribution of secondary particles charge reconstruction efficiency Inefficiency  Charge = 0 Charge efficiency = (2848-27)/2848 = 99.1±0.2%

16. Carbon interaction Bragg peak Contamination at the % level Track multiplicity

17. Angular distribution of secondary particles Elastic scattering Hydrogen Helium large angle (a few percent) Lithium

18. Cross-section measurement A volume of about 24cm 3 was analyzed 2306 interaction vertices found (475 elastic) The number of events with maximal charge as Lithium (  z = 3) is 183, as beryllium (  z = 2) is 118, as Boron (  z = 1) is 258 Toshito et al.

19. Interaction length for different secondary ions

20. Very preliminary 8Be  He + He (10 -16 s) Q value 90 keV   (rad) He Real event He-proton opening angle

21. Conclusions The charge separation capability is about 5 sigma for protons and helium already with less than 10 plates where other detectors fail The separation between boron and carbon requires 30 plates to reach 2.5 sigma Emulsions provide unprecedented results in the light ion identification Preliminary results cross-section measurement Possible improvements Improve the identification capability for short tracks Measure the momentum for isotope discrimination Extend the energy range for cross-section measurements