A 12-MHz CW RFQ for the AEBL Project

D. L. Schrage,P. N. Ostroumov,A. Barcikowski,D. Fallin,A. A. Kolomiets 한국물리학회 2008 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.52 No.3

The Advanced Exotic Beam Laboratory (AEBL) at the Argonne National Laboratory (ANL) will provide a research facility for studies of nuclear phenomena by using beams of short-lived isotopes for research on the nature of nucleonic matter and the origin of the elements, for tests of the Standard Model, for applications in medicine and industry, and for other applied physics research. The proposed design of the AEBL driver linac evolved from the Rare Isotope Accelerator (RIA) project. The AEBL will be a CW linac capable of accelerating uranium ions up to 200 MeV/u and protons to 580 MeV with 400 kW beam power. The AEBL facility also includes a post-accelerator which is designed for acceleration of radioactive ions with charge-to-mass ratios in the range from 1/238 to 1/6. Very low charge-state ions can be most eciently bunched and accelerated by using normally-conducting radio-frequency quadrupole (RFQ) for the rst few MV of the post accelerator. A two-meter long, 12-MHz CW RFQ was designed, built, and tested in the late 1990s as the rst section of a three-section RFQ [18]. This RFQ achieved inter-electrode voltages of 110 kV CW (the peak surface eld was 15 MV/m) and accelerated beams with A/q as large as 132 (132Xe). The AEBL requires a similar RFQ for the post-acceleration of singly-charged unstable nuclides. Our plan is to replace the vanes of this RFQ with a design that incorporates a stronger focusing and that will achieve a higher peak surface eld (16 MV/m) at 82.2-kV inter-vane voltage. The objectives of this project are 1. to conrm the possibility of a low injection energy of 0.4 keV/u which signicantly reduces the voltage required for a high-voltage deck; 2. to test the highest possible peak surface eld on the RFQ electrodes designed for the lowest frequency of 12 MHz compared to existing RFQs worldwide; 3. to provide a technical base for the design of a post-accelerator for the future Advanced Exotic Beam Facility. At the present time, the design is complete, and the fabrication of the 12 MHz RFQ is scheduled to commence in October 2007 with testing planned in 2008. The physics and engineering design of the RFQ is discussed. The Advanced Exotic Beam Laboratory (AEBL) at the Argonne National Laboratory (ANL) will provide a research facility for studies of nuclear phenomena by using beams of short-lived isotopes for research on the nature of nucleonic matter and the origin of the elements, for tests of the Standard Model, for applications in medicine and industry, and for other applied physics research. The proposed design of the AEBL driver linac evolved from the Rare Isotope Accelerator (RIA) project. The AEBL will be a CW linac capable of accelerating uranium ions up to 200 MeV/u and protons to 580 MeV with 400 kW beam power. The AEBL facility also includes a post-accelerator which is designed for acceleration of radioactive ions with charge-to-mass ratios in the range from 1/238 to 1/6. Very low charge-state ions can be most eciently bunched and accelerated by using normally-conducting radio-frequency quadrupole (RFQ) for the rst few MV of the post accelerator. A two-meter long, 12-MHz CW RFQ was designed, built, and tested in the late 1990s as the rst section of a three-section RFQ [18]. This RFQ achieved inter-electrode voltages of 110 kV CW (the peak surface eld was 15 MV/m) and accelerated beams with A/q as large as 132 (132Xe). The AEBL requires a similar RFQ for the post-acceleration of singly-charged unstable nuclides. Our plan is to replace the vanes of this RFQ with a design that incorporates a stronger focusing and that will achieve a higher peak surface eld (16 MV/m) at 82.2-kV inter-vane voltage. The objectives of this project are 1. to conrm the possibility of a low injection energy of 0.4 keV/u which signicantly reduces the voltage required for a high-voltage deck; 2. to test the highest possible peak surface eld on the RFQ electrodes designed for the lowest frequency of 12 MHz compared to existing RFQs worldwide; 3. to provide a technical base for the design of a post-accelerator for the future Advanced Exotic Beam Facility. At the present time, the design is complete, and the fabrication of the 12 MHz RFQ is scheduled to commence in October 2007 with testing planned in 2008. The physics and engineering design of the RFQ is discussed.

Spectroscopic properties of phenolic and quinoid carotenoids: a combined theoretical and experimental study

Marian, Christel M.,Kock, Sebastian C.,Hundsdorfer, Claas,Martin, Hans-Dieter,Stahl, Wilhelm,Ostroumov, Evgeny,Muller, Marc G.,Holzwarth, Alfred R. Korean Society of Photoscience 2009 Photochemical & photobiological sciences Vol.8 No.2

For the natural carotenoid 3,3'-dihydroxyisorenieratene (DHIR) and two synthetic derivatives, 3,3'-dihydroxy-16,17,18,16',17',18'-hexanor-$\Phi$,$\Phi$-carotene (DHHC) and $\Phi$,$\Phi$-carotene-3,3'-dione (DHIRQ, isorenieratene-3,3'-dione), steady state absorption experiments and combined density functional and multi-reference configuration interaction calculations were carried out. In addition, femtosecond transient absorption spectra were recorded for DHIR. Due to their marked out-of-plane distortion in DHIR, the phenolic end groups participate only partially in the conjugation system. In the low-energy regime its absorption spectrum with the maximum at $21\;700\;cm^{-1}$ in acetone solution therefore closely resembles that of $\beta$-carotene, the same as for the $T_1$ energy. Further similarities are also found for the decay kinetics of the optically bright $1^1{B_u}^+$ state of these compounds. After femtosecond excitation, the $1^1{B_u}^+$ population of DHIR decays with a lifetime of 110 fs to the vibrationally hot $2^1{A_g}^-$,v state which in turn relaxes to the $2^1{A_g}^-$,0 state within 500 fs. Decay of the $2^1{A_g}^-$,0 state to the $S_0$ state occurs at a time scale of 12 ps. Demethylation of the phenolic end groups alleviates the steric repulsion by the polyene chain and causes a small red shift ($1000\;cm^{-1}$) comparing the absorption spectra of DHHC and DHIR. Oxidation of DHIR leads to drastic changes of the electronic and geometric properties. The quinoid end groups of DHIRQ are fully integrated into the conjugation system, shifting the absorption maximum to $17\;800\;cm^{-1}$ in acetone solution which thus takes a blue color. The results of the quantum chemical calculations indicate that, in addition to the $2^1{A_g}^-$ ($S_1$) state, two dark internal charge-transfer singlet states and the $1^1{B_u}^-$ state might be located energetically below the optically bright $1^1{B_u}^+$ ($S_5$) state of DHIRQ.

A 57-MHz CW RFQ for the AEBL Project

D.L. Schrage,A. Barcikowski,A.A. Kolomiets,B. Rusthoven,B. Clifft,F. DePaola,G. Waldschmidt,J.W. Rathke,M. Bracken,N.E. Vinogradov,P.N. Ostroumov,S. Sharma,S.I. Sharamentov,T. Schultheiss,W. F. Toter 한국물리학회 2007 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.50 No.I

The Advanced Exotic Beam Laboratory (AEBL) at the Argonne National Laboratory (ANL) will provide a research facility for studies of nuclear phenomena by using beams of short-lived isotopes for research in the nature of nucleonic matter, the origin of the elements, tests of the Standard Model along with applications in medicine, industry, and other applied physics research. The proposed design of the AEBL driver linac evolved from the Rare Isotope Accelerator (RIA) project. It is a CW 850 MV linac capable of accelerating uranium ions up to 200 MeV/u and protons to 570 MeV with 400 kW beam power. The first section of the linac is a 57 MHz pseudo split coaxial CW Radio Frequency Quadrupole (RFQ) linac. This is followed by 221 superconducting cavities of various types. A section of the RFQ linac was fabricated and tested under R\&D funding for the RIA Project. This is the first section of the six-section, 392 cm RFQ linac. This paper describes the design, fabrication, and testing of this RFQ.