1. 24th International Conference on Nuclear Tracks in Solids Bologna, 1-5/9/2008
Fragmentation cross sections of Fe26+, Si14+ and C6+ ions of 0.310 A GeV on polyethylene, CR39 and aluminum targets
M. Giorgini* on behalf of the Bologna group
*Bologna University and INFN

2. MOTIVATIONS
An accurate description of the fragmentation of medium and high Z ions is important for the following reasons :
(i) to understand the effects of medium Z cosmic rays on humans
in space
(ii) for shielding in space and in accelerator environments
(iii) for radiotherapy and radioprotection purposes
(iv) to confirm the simulated data from the FLUKA* and RQMD**
(Relativistic Quantum Molecular Dynamics) Monte Carlo codes
* hep-ph/
** J. Phys. Conf. Ser. 41 (2006) 519

3. EXPERIMENTAL PROCEDURE
Survived beam
Fragments
Incident beam
CR39 Detectors
Target
Beam : Fe26+ (E = 0.3 , 0.41 , 1.0 , 3.0 , 5.0 AGeV)
Si14+ (E = 1.0 , 3.0 , 5.0 AGeV)
C6+ (E = 0.29 AGeV)
CR39 sheets : area 11.5 × 11.5 cm2
thickness mm
Targets : CH2 , Al , CR39
thickness 1 mm
After exposure, the CR39 sheets were etched in 6N NaOH aqueous solution at 70 °C for 30 h

4. AUTOMATIC MEASUREMENTS
Automatic image analyzer ELBEK
(A. Noll et al., Nucl. Tracks Radiat. Meas. 15 (1988) 265)
The base area, eccentricity and brightness are measured for each track
Tracking : the trajectory of each ion is followed through the stack
5 AGeV Fe26+
1 AGeV Fe26+
Number of events
Number of events
Average base areas for tracks present in at least 2 out of 3 measured CR39 sheets located before the target
Average base areas for tracks present in at least 2 out of 3 measured CR39 sheets located after the target

5. TOTAL FRAGMENTATION CROSS SECTION
stot =
AT ln(Nin/Nout)
rT tT NAV
AT = mass number of the target
rT = density of the target
tT = thickness of the target
NAV = Avogadro's number
Nin = number of incident ions before the target
Nout = number of incident ions after the target
ZT = atomic number of the target
Ap = mass number of the beam
ro = 1.31 fm
bo = 1.0
 = 1.57
 = 1.9

6. FRAGMENTATION CROSS SECTIONS OF Fe26+ ON CH2 , CR39 AND Al
Fe26+ on Al
Fe26+ on CH2
[ Phys. Rev. C 56 (1997) 388 ]
Total cross section (mb)
Energy (AGeV)
Target AT
stot (mb) 10
CH2
4.7
1147 ± 97
CR39
7.4
1105 ± 360 5
1041 ± 130
1170 ± 470 3
904 ± 140
1166 ± 67 1
1105 ± 60
1113 ± 176 Al 27
1870 ± 131
0.41
948 ± 54
1285 ± 245
1950±126
0.30
949 ± 61
1174 ± 192
2008±144
The quoted uncertainties are statistical standard deviations

7. FRAGMENTATION CROSS SECTIONS OF Si14+ ON CH2 , CR39 , Al , C e H
Si14+ on Al
Si14+ on CH2
Si14+ on CR39
[ Phys. Rev. C 39 (1989) 2222 ]
[ Radiat. Meas. 34 (2001) 237 ]
[ Nucl. Phys. A 784 (2007) 341 ]
Total cross section (mb)
Energy (A GeV)
Target
σtot (mb) 5
CH2
757 ± 168 3 Al
1533 ± 133 1
CR39
1113 ± 176 H
483 ± 76
694 ± 70 C
1117 ± 62
1397 ± 138
The quoted uncertainties are statistical standard deviations

8. DATA-PREDICTIONS COMPARISON
[ Phys. Rev. C 56 (1997) 388 ]
Total cross section (mb)
Target mass AT
0.29 A GeV C Present work
Total cross section (mb)
[ Phys. Rev. C 39 (1989) 2222 ]
[ Nucl. Phys. A 784 (2007) 341 ]
[ Phys. Rev. C 66 (2002) ]
Target mass AT

9. PARTIAL CHARGE CHANGING CROSS SECTIONS
Average base areas for tracks present in at least 2 out of 3 measured CR39 sheets located after the target
Charge resolution sZ ~ 0.2e

10. PARTIAL CHARGE CHANGING CROSS SECTIONSDZ
sDZ (mb) -1 -
293 ± 18 -2
338 ± 11
177 ± 12 -3
285 ± 11
123 ± 11 -4
252 ± 10
122 ± 11 -5
249 ± 10
62 ± 8 -6
197 ± 9
117 ± 11 -7
168 ± 8
83 ± 9 -8
132 ± 7
90 ± 10 -9
175 ± 8
-10
107 ± 7
-11
152 ± 6
-12
105 ± 8
-13
103 ± 6
-14
81 ± 6
-15
80 ± 6
-16
50 ± 4
-17
76 ± 5
-18
86 ± 6
Partial fragmentation charge
changing cross sections for
1 AGeV Si14+ and 1 AGeV Fe26+ ions on the CH2 target
The quoted uncertainties are statistical standard deviations

11. CONCLUSIONS
The total fragmentation cross sections for Fe26+, Si14+ and C6+ ion beams of 0.3  10 A GeV energies on polyethylene, CR39 and aluminum targets were measured using CR39 nuclear track detectors
The total cross sections for all the targets and energies used in the present work do not show any observable energy dependence
There is a dependence on target mass.
The highest cross section values, observed for Al targets, are mainly due to the contribution of electromagnetic dissociation
The present data of total fragmentation cross sections are in agreement with similar experimental data in the literature
The presence of well separated fragment peaks allowed the determination of the partial fragmentation cross sections. On the average the partial cross sections decrease as the charge change DZ increases
The measured cross section data indicate that the CR39 detector can be used effectively for studies of the total and partial charge changing cross sections, also in comparison with active detectors