The FRAGM experiment is carried out on the basis of the ITEP–TWAC multipurpose accelerator complex, which generated proton and ion beams for various studies in the field of nuclear physics. A ...technique for identifying fragments in secondary ion beams based on the analysis of correlation distributions over the time of flight and signal amplitude from scintillation detectors is presented. The experimental data are obtained by fragmentation of a carbon beam with energy of 300 MeV per nucleon by scanning the rigidity of the magneto-optical channel with a step of 50 MeV/
c
. Differential cross sections for ion production are obtained using beryllium isotopes as an example. The results are compared with the predictions of the binary cascade model.
The results of searches for nucleon charge-exchange processes in the fragmentation of carbon ions are presented. The respective experimental data were obtained by means of the FRAGM facility at the ...TWAC-ITEP multipurpose accelerator complex with a 300-MeV/nucleon beam incident to a thin beryllium target. The experimental setup used, which was oriented at an angle of 3.5
with respect to the ion beam, possessed a hodoscope system, which ensured an accuracy of 0.4
in momentum measurements. The differential cross sections for the yields of isotopes
Be and
B produced upon single nucleon charge exchange were measured as a function of the fragment momentum. These experimental data were compared with theoretical predictions of two models of ion–ion interactions: the binary cascade (BC) model and the intranuclear cascade (INCL) model. In the above energy range, processes of nucleon charge exchange were measured for the first time.
In the FRAGM experiment at the heavy-ion accelerator
accumulator complex ITEP
TWA, yields of cumulative charged
mesons have been measured in a fragmentation of carbon ions with the energy of 3.2 ...GeV/nucleon on a beryllium target. The momentum spectra of
mesons cover four orders of the invariant cross section magnitude. They demonstrate the exponential fall with increasing energy. The measured inverse slope parameter is compared with similar measurements in nucleon–nucleus interactions and ion–ion collisions at lower energies. The energy dependence of the ratio of the yields of negative to positive
mesons is presented. This dependence is discussed in a connection with Coulomb and isotopic effects. The obtained data are compared with predictions of several ion–ion interaction models.
Experimental data are presented on differential cross sections of the formation of
11
Be,
12
Be, and
12
B isotopes. The isotopes form upon the fragmentation of a carbon beam at 300 MeV/nucleon in the ...FRAGM experiment performed at the multipurpose ITEP−TWAC accelerating complex. The experimental data are compared to predictions made with the binary cascade and quantum molecular dynamic models of ion–ion interaction.
The differential cross sections for the yields of nuclear fragments at an angle of 3.5◦ in the fragmentation of carbon nuclei with energy 0.95 GeV per nucleon on a beryllium target were measured in ...the FRAGM experiment at the ITEP TWA heavy-ion accelerator. The momentum spectra of fragments were used to test the following four models of ion–ion interactions: BC, INCL++, LAQGSM03.03, and QMD. For light fragments, the slope parameters of the kinetic-energy spectra were obtained in the cumulative region.
Momentum spectra of all long-lived fragments from 12C fragmentation at 3.5° have been measured. Differential cross sections span up to five orders of its magnitude. The preliminary results are ...compared with predictions of two transport codes: INCL++ and LAQGSM03.03. Both models give a good description of the data except few items which are discussed.
The yields of long-lived nuclear fragments at an angle of 3.5° that originate fromthe fragmentation of carbon ions with an energy of
T
0
= 0.6 GeV per nucleon on a berylliumtarget were measured in ...the FRAGMexperiment at the ITEP TWA heavy-ion accelerator. The momentum spectra of these fragments cover both the fragmentation-maximum region and the cumulative region. The respective differential cross sections change by about five orders of magnitude. The momentum distributions of fragments in the laboratory frame and their kinetic-energy distributions in the rest frame of the fragmenting nucleus are used to test the predictions of four models of ion–ion interactions: BC, INCL++, LAQGSM03.03, and QMD.
Fast macromolecular proton fraction mapping is a recent quantitative MR imaging method for myelin assessment. The objectives of this study were to evaluate the macromolecular proton fraction as a ...measure of demyelination in subcortical GM structures in multiple sclerosis and assess a potential relationship between demyelination and excess iron deposition using the macromolecular proton fraction and T2* mapping.
Macromolecular proton fraction and T2* maps were obtained from 12 healthy controls, 18 patients with relapsing-remitting MS, and 12 patients with secondary-progressive MS using 3T MR imaging. Parameter values in the caudate nucleus, globus pallidus, putamen, substantia nigra, and thalamus were compared between groups and correlated to clinical data.
The macromolecular proton fraction in all subcortical structures and T2* in the globus pallidus, putamen, and caudate nucleus demonstrated a significant monotonic decrease from controls to patients with relapsing-remitting MS and from those with relapsing-remitting MS to patients with secondary-progressive MS. The macromolecular proton fraction in all subcortical structures significantly correlated with the Expanded Disability Status Scale and MS Functional Composite scores with absolute Pearson correlation coefficient (
) values in a range of 0.4-0.6. Significant correlations (
= -0.4 to -0.6) were also identified between the macromolecular proton fraction and the 9-Hole Peg Test, indicating a potential relationship with nigrostriatal pathway damage. Among T2* values, weak significant correlations with clinical variables were found only in the putamen. The macromolecular proton fraction did not correlate with T2* in any of the studied anatomic structures.
The macromolecular proton fraction provides an iron-insensitive measure of demyelination. Myelin loss in subcortical GM structures in MS is unrelated to excess iron deposition. Subcortical GM demyelination is more closely associated with the disease phenotype and disability than iron overload.
Momentum distributions of hydrogen and helium isotopes from 12C fragmentation at 3.5° were measured at 0.6 GeV/nucleon in the FRAGM experiment at ITEP TWA heavy ion accelerator. The fragments were ...selected by correlated time of flight and dE/dx measurements with a magnetic spectrometer with scintillation counters. The main attention was drawn to the high momentum region where the fragment velocity exceeds the velocity of the projectile nucleus. The momentum spectra of fragments span the region of the fragmentation peak as well as the cumulative region. The differential cross sections cover six orders of magnitude. The distributions measured are compared to the predictions of three ion-ion interaction models: BC, QMD and LAQGSM03.03. The kinetic energy spectra of fragments in the projectile rest frame have an exponential shape with two temperatures, being defined by their slope parameters.
Momentum spectra of all long lived fragments from 12C fragmentation at 3.5o on different targets have been measured. Obtained fragmentation peak widths are compared with predictions of statistical ...model. An independence of these widths from target nuclei has been checked with high precision.