Search results for "ionit"
showing 10 items of 142 documents
The ion-optical design of the MARA recoil separator and absolute transmission measurements of the RITU gas-filled recoil separator
2011
In this thesis work, the use of two complementary recoil separators for studies of nuclear structure via fusion-evaporation reactions are discussed. The design and the main ion-optical properties of the vacuum-mode recoil-mass separator MARA, intended for studies of nuclei with N Z close to the proton drip-line, are presented. MARA (Mass Analysing Recoil Apparatus) consists of a magnetic quadrupole triplet followed by an electrostatic de ector and a magnetic dipole. The working principle of MARA is discussed and the reasons for the choice of the optical parameters of the elements are given. The performance of MARA for di erent kind of fusion reactions has been studied with Monte Carlo simul…
RITU:n kehittäminen ja kaasutäytteisiin separaattoreihin liittyvää ionioptiikkaa
2004
ECR-ionilähteen tuottaman röntgensäteilyn simulointi
2008
Central Region Upgrade for the Jyväskylä K130 Cyclotron
2020
The Jyväskylä K130 cyclotron has been in operation for more than 25 years providing beams from H to Au with energies ranging from 1 to 80 MeV/u for nuclear physics research and applications. At the typical energies around 5 MeV/u used for the nuclear physics program the injection voltage used is about 10 kV. The low voltage limits the beam intensity especially from the 18 GHz ECRIS HIISI. To increase the beam intensities the central region of the K130 cyclotron is being upgraded by increasing the injection voltage by a factor of 2. The new central region with spiral inflectors for harmonics 1-3 has been designed. The new central region shows better transmission in simulations than the origi…
Dijet studies with ALICE at the LHC
2020
Relativistisissa hiukkastörmäyksissä syntyvistä suurenergisistä kvarkeista ja gluoneista, eli partoneista, muodostuvaa hyvin kollimoitunutta hiukkassuihkua kutsutaan jetiksi. Jettien tutkimusta on tehty jo vuosikaudet ja se hallitaan hyvin myös raskasionitörmäyksissä, joissa muodostuvaa kvarkkigluoniplasmaa on pystytty tutkimaan jettien liikemäärähäviöiden avulla. Tämän perusteella on huomattu, että kvarkkigluoniplasma jarruttaa sen läpi kulkevia suurenergisiä partoneita. Jettien lisäksi partonien energiahäviöitä raskasionitörmäyksessä on tutkittu myös dijettien avulla. Dijetti on määritelty törmäyksen kahdesta suurimman energian omaavasta jetistä muodostuvaksi systeemiksi. Aiempien RHIC- j…
Fenyyli-ja metoksifenyylisubstituoidut karbokationit katalyytteinä
2018
Karbokationit ovat orgaanisia molekyylejä, joissa on positiivisesti varautunut hiiliatomi. Hybridisaatioteoria selittää karbokationien luonnetta ja kolmiulotteista rakennetta keskushiilen sp2-hybridisaatiolla, jossa hiiliatomin hybridisoitumaton p-orbitaali levittäytyy kolmen hybridiorbitaalin muodostaman tason ylä- ja alapuolille. Hybridisoitumaton porbitaali ei kuitenkaan ole täysin eristyksissä hybridisoituneista sidosorbitaaleista vaan se vastaanottaa helposti elektronitiheyttä keskushiileen sitoutuneilta substituenteilta. Mitä enemmän substituentit luovuttavat elektronitiheyttä positiivisesti varautuneelle hiiliatomille, sitä enemmän elektronitiheyttä siirtyy myös hybridisoitumattomall…
Anion Responsive Molecular Switch Based on a Doubly‐Strapped Calix[4]pyrrole
2022
A calix[4]pyrrole receptor bearing two proximally meso - meso linking isophthaloyl straps displays open and closed states depending on the calix[4]pyrrole conformation. In the crystal structures and in non-polar solvent, the calix[4]pyrrole adopts open 1,3-alternate conformation with straps on the sides. Anion binding triggers a closed state of the receptor providing two types of interactions with an aromatic benzoate guest: hydrogen bonds from the pyrrolic groups and π ··· π interactions from the phenyl groups of the straps. Slow exchange dynamics was observed on the NMR timescale indicating that benzoate, acetate and chloride anions, which bind with relatively low affinity get kinetically…
Separation of atomic and molecular ions by ion mobility with an RF carpet
2021
Gas-filled stopping cells are used at accelerator laboratories for the thermalization of high-energy radioactive ion beams. Common challenges of many stopping cells are a high molecular background of extracted ions and limitations of extraction efficiency due to space-charge effects. At the FRS Ion Catcher at GSI, a new technique for removal of ionized molecules prior to their extraction out of the stopping cell has been developed. This technique utilizes the RF carpet for the separation of atomic ions from molecular contaminant ions through their difference in ion mobility. Results from the successful implementation and test during an experiment with a 600~MeV/u $^{124}$Xe primary beam are…
Room-Temperature Magnetic Bistability in a Salt of Organic Radical Ions
2021
International audience; Cocrystallization of 7,7′,8,8′-tetracyanoquinodimethane radical anion (TCNQ −•) and 3-methylpyridinium-1,2,3,5dithiadiazolyl radical cation (3-MepyDTDA +•) afforded isostructural acetonitrile (MeCN) or propionitrile (EtCN) solvates containing cofacial π dimers of homologous components. Loss of lattice solvent from the diamagnetic solvates above 366 K affords a high-temperature paramagnetic phase containing discrete TCNQ −• and weakly bound π dimers of 3-MepyDTDA +• , as evidenced by X-ray diffraction methods and magnetic susceptibility measurements. Below 268 K, a first-order phase transition occurs, leading to a low-temperature diamagnetic phase with TCNQ −• σ dimer…
Molecular dynamics simulations of heavy ion induced defects in SiC Schottky diodes
2018
Heavy ion irradiation increases the leakage current in reverse-biased SiC Schottky diodes. This letter demonstrates, via molecular dynamics simulations, that a combination of bias and ion-deposited energy is required to produce the degradation. Peer reviewed