F. Bianchi

F. Groppi

G. Harki

S. Manenti

English

AIR Universita degli studi di Milano

Cross-Section measurements for the Reaction natCr(d,x)52g,cumMn: Preliminary Results  
F. Bianchi1, G. Harki2,1, F. Groppi1, S. Manenti1 
1 LASA, Physics Department, Università degli Studi di Milano, and INFN, Milano, Italy.  2 Physics Department, Salahaddin 
University, Erbil, Iraq. 
 
 
INTRODUCTION 
Manganese-52 (52Mn) is a radionuclide that decays 
through both positron emission and EC modes, with a 
medium-long half-life (t1/2 = 5.591 d). 
As a positron emitter, Mn-52 has a possible use in nuclear 
medicine as a radiotracer for PET, useful to investigate 
biological and physiological processes occurring on the 
same time scale of its decay; the low energy of the positrons 
emitted (244.6 keV) and the short range in the  tissues  
(0.63 mm) [1] would allow to acquire diagnostic images of 
a quality similar to those obtained with radiotracers already 
in use, such as fluorine-18 (250 keV; 0.62 mm) [2].  
Moreover, the transition element manganese, has stable 
isotopes with useful paramagnetic properties for MRI 
procedures. 
Goal of the approved METRICS research project, funded 
by CSN5 INFN, is thus to develop a new approach, based 
upon a perfect molecular matching probe, for both PET and 
MRI, by using paramagnetic and radioactive manganese 
isotopes to afford an unprecedented type of multi-modal 
(MMI) PET/MRI hybrid imaging. 
Currently manganese is produced by irradiation with 
protons on chromium targets; production with deuteron 
beams could be more advantageous in terms of higher 
yields: an accurate knowledge of thin-target excitation 
function for natCr(d,x)52Mn reaction is necessary for this 
purpose to determine purity as well. 
Published data are scarce and rather dated: the aim of the 
present work, carried out by the INFN LASA research group 
in the framework of METRICS project, was therefore to 
provide more experimental data. A wide energy range, from 
6 MeV up to 29 MeV, for the production of the radionuclide 
concerned was investigated. 
The determination of the best irradiation parameters using 
deuterons, to yield 52Mn, in as high as possible radionuclidic 
purity form, for the MMI approach with the new hybrid 
PET/MRI tomography now available, is therefore 
mandatory. 
EXPERIMENTAL 
The excitation functions were measured by using the 
stacked-foils technique, covering the deuteron energy range 
from 6 MeV to 29 MeV. Stacks of thin foils consist of 
alternating series of chromium layers having natural 
isotopic composition (4.35% 50Cr, 83.79% 52Cr, 9.5% 53Cr, 
2.36% 54Cr), high purity aluminum ones (acting as both 
energy degrader and monitor reaction foils), ended by a 
titanium layer, as final monitor foil.  
In particular, four prepared stacks, contained 4 Cr targets, 
16 Al foils and 4 Ti monitor foils, were irradiated at different 
beam energies. 
natCr foils were prepared, with a nominal thickness of 
about 20 μm and a general relative uncertainty of ±2%, by 
the Department of Chemistry, Materials and Chemical 
Engineering “Giulio Natta” of Milan Polytechnic, by electro 
deposition technique on 16 μm thick Al foils. The true value 
of target thickness was accurately determined by a weighing 
procedure afterwards. 
All irradiations were carried out with the cyclotron  
(AVF IBA-C70XP, K = 70, beam current up to 2x375 μA) 
of ARRONAX facility located in Saint-Herblain (FR) at 
different incident energies with a constant current of about 
150 nA for a duration of 1 h. The excitation functions were 
obtained from four foil stacks irradiated in four different 
irradiation experiments. After the irradiations the targets 
were delivered with the authorized transportation service to 
LASA in Segrate (MI) to perform all the scheduled 
measurements stage. 
The activity was measured, without any chemical 
processing, by using a calibrated high purity germanium 
(HPGe) detector (EG&G Ortec, 15% relative efficiency, 
FWHM = 2.2 keV at 1.33 MeV). All foils were measured in 
the same geometrical configuration as that used for the 
detectors calibration sources in order to avoid corrections 
for different geometries. The distance from the detector cap 
was chosen in order to reduce dead time and pile up errors 
to negligible values (< 0.1%). The first measurements of the 
samples were started within few days after end of 
bombardment (EOB) and measurements continued 
periodically for about 4-5 months to follow the decay of 
manganese-52:  
in general the counts in the peak in the region of interest 
exceed 10 000. 
 
RESULT AND DISCUSSION 
The foils of the stacked foil targets were measured, 
positioning them on the detector with the beam-on side 
showing towards the detector cup. The experimental  
cross-sections σ(E) [cm2 = 1027mb] for each target were 
calculated from equation (1), taking into account also the 
decay factor to correct for the decay during the counting 
time (D(tcount)) and the growing factor to correct the decay 
during the irradiation time (G(tirr)):  
 𝜎(𝐸) =
𝐴∙𝑀∙Z∙e
𝜌𝑥∙𝑁𝐴∙𝑄∙𝜆
∙ 𝐺(𝑡𝑖𝑟𝑟) ∙ 𝐷(𝑡𝑐𝑜𝑢𝑛𝑡) ∙ 𝑒
𝜆∙∆t , (1) 
 
 
with: 
 
𝐷(𝑡𝑐𝑜𝑢𝑛𝑡) =
𝜆𝑡𝑐𝑜𝑢𝑛𝑡
1−𝑒−𝜆𝑡𝑐𝑜𝑢𝑛𝑡
 ,                                 (2) 
 
𝐺(𝑡𝑖𝑟𝑟) =
𝜆𝑡𝑖𝑟𝑟
1−𝑒−𝜆𝑡𝑖𝑟𝑟
 ,                                 (3) 
 
where A is the activity [Bq], M denotes the atomic mass 
[g·mol-1], NA is Avogadro’s constant [atom·mol-1],  
e the electron charge [C], Z the atomic number of the 
projectile, λ the decay constant [s-1] of the investigated 
radionuclide, Q is the integrated deuteron charge [C],  
ρx the mass thickness [g·cm-2] of the target, and Δt the 
waiting time from the EOB [s].    
52Mn has also a metastable level (t1/2 = 21.1 m) at  
E = 377.749 keV, that decays for a small fraction  
(IT = 1.085%) by isomeric transition to the longer lived 
ground state. In our experimental conditions it was not 
possible   to   measure   this    contribution    separately:  
the results reported also take into account the cumulative 
production of 52mMn. 
The experimental data are compared with theoretical 
prediction reported in the TENDL 2017 [3] on-line library 
obtained with the TALYS code. 
In Fig 1 the experimentally measured excitation function 
for natCr(d,x)52g,cumMn reaction route is reported, compared 
to past experimental data available in literature [4-10] as 
well as that from simulation. These are preliminary results 
being evaluated; for this reason, error bar is not given. 
Fig. 1. Excitation function for natCr(d,x)52g,cumMn nuclear reaction. 
In the study of 52Mn production, we must consider also 
the production of the long half-life radionuclide 54Mn   
(t1/2 = 312.2 d) as a radioisotopic impurity. 
In Fig 2 the experimentally measured cross-section for the 
natCr(d,x)54Mn reaction route is reported, compared with the 
few data present in literature [4,5,9], and with the expected 
result from TENDL 2017 simulation. 
Data obtained in this work result lower than published 
data. Also theoretical data from TENDL 2017 overestimate 
the experimental cross-sections. 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Fig. 2. Excitation function for natCr(d,x)54Mn nuclear reaction. 
CONCLUSION 
The excitation functions of the nuclear reactions 
natCr(d,x)52g,cumMn and natCr(d,x)54Mn were measured 
covering the deuteron energy range from 6 MeV to 29 MeV. 
As obtained from the experimental preliminary results 
reported in this paper, the optimal energy range for the 
production of 52Mn via cyclotron route is 28–12 MeV.  
In fact, the cross-section reaches its maximum value in this 
energy range. Furthermore, in this range the production of 
the long-lived radioisotopic impurity due to 54Mn is 
minimized. Further investigations and comparison analyses 
with the proton-driven routes for 52Mn production are 
underway. 
 
 
 [1] C. Le Loirec, C. Champion, Nucl. Instrum. Methods Phys. 
Res. A582 (2007) 654. 
 [2] A. Disselhorst et al., J. Nucl. Med. 51 (2010) 610. 
 [3] A.J. Koning and D. Rochman, Nuclear Data Sheets 113 
(2012) 2841. 
 [4] E. Simeckova et al., Phys. Rev. C98 (2018) 034606. 
 [5] A. Hermanne et al., Nucl. Instrum. Methods Phys. Res. 
B269 (2011) 2563. 
 [6] H.I. West et al., Phys. Rev. C35 (1987) 2067. 
 [7] M. Cogneau, L. Gilly, J. Cara, Nucl. Phys 79 (1966). 
 [8] Cheng Xiaowu et al., Acta Physica Sinica 22 (1966) 250. 
 [9] P. Kafalas, J.W. Irvine, Phys. Rev. 104 (1956) 703. 
[10] W.H. Burgus et al., Phys. Rev. 95 (1954) 750.  


Cross-Section measurements for the Reaction natCr(d,x)52g,cumMn:Preliminary Results

https://air.unimi.it/bitstream/2434/669721/2/151_D_101_D096.pdf

Cross-Section measurements for the Reaction natCr(d,x)52g,cumMn:Preliminary Results

Abstract

Similar works

Full text

Available Versions

AIR Universita degli studi di Milano