HB2014 - Table of Session: THO1AB (Working Group E)

Paper

Title

Page

Simultaneous Acceleration of Radioactive and Stable Beams in the ATLAS Linac

334

B. Mustapha, P.N. Ostroumov
ANL, Argonne, USA
M.A. Fraser
CERN, Geneva, Switzerland
A. Perry
Illinois Institute of Technology, Chicago, Illlinois, USA

Funding: This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics, under contract number DE-AC02-06CH11357.
ATLAS is now the only US DOE National User Facility for low-energy heavy-ion stable beams. With the recent commissioning of the Californium Rare Isotope Breeder Upgrade (CARIBU), ATLAS is now also used to accelerate radioactive beams. The demand for both stable and radioactive beam time is already exceeding two to three times the 5500 hours delivered by ATLAS every year. The time structure of the EBIS charge breeder to be installed next year for CARIBU beams is such that only 3% of the ATLAS duty cycle will be used for radioactive beams. Being a CW machine, 97% of the ATLAS cycle will be available for the injection and acceleration of stable beams without retuning. This simultaneous acceleration is possible for stable and radioactive beams with charge-to-mass ratios within 3%. We have developed a strategic plan to upgrade ATLAS for this purpose over the next few years, where two to three beams could be delivered simultaneously to different experimental areas. The upgrade concept will be presented and discussed along with the recent studies and developments done in this direction.

Slides THO1AB01 [1.829 MB]

THO1AB02

Experience with Stripping Heavy Ion Beams

340

H. Okuno
RIKEN Nishina Center, Wako, Japan

Charge strippers play a critical role in many high intensity heavy ion accelerators. The recent progress on accelerator technology makes its role so critical that traditional carbon foils easily reach the limit of application due to their short lifetime. In fact the major heavy ion accelerator facilities such as GSI, MSU/ANL and RIKEN have made elaborating efforts to develop the alternatives to the carbon foils, in order to realize acceleration of very heavy ions such as uranium with high intensity. For example liquid lithium stripper has been developed at MSU/ANL and helium gas stripper and rotating Be disk stripper have been developed at RIKEN RIBF. The two strippers for RIBF greatly contributed to increase of the uranium beam intensity. However we are sure that Be disk stripper used for the second stripper will reach the limit in near future due to its large deformation, which require further developments for our intensity upgrade program.

Slides THO1AB02 [11.042 MB]

THO1AB03

BNL Electron Beam Ion Sources: Status and Challenges

A.I. Pikin, J.G. Alessi, E.N. Beebe
BNL, Upton, Long Island, New York, USA
R. Scrivens, A. Shornikov, F.J.C. Wenander
CERN, Geneva, Switzerland

Funding: US Department of Energy and the National Aeronautic and Space Administration
The Electron Beam Ion Source (EBIS) at the Brookhaven National Laboratory (BNL) is a main source of highly charged ions for both Relativistic Heavy Ion Collider (RHIC) and NASA Space Radiation Laboratory (NSRL). It has delivered a wide variety of ions since 2010 with good stability and reliability. The ongoing development of the electron gun with electrostatic compression has a goal to significantly increase the current density of the electron beam. Such electron beam would allow boosting the charge state of ions, which RHIC EBIS injects into RFQ and therefore to increase their final energy at Booster for NSRL applications. This development can also benefit ISOLDE experiment at CERN, where high charge state of the extracted ions is as important as a large acceptance of EBIS and high repetition rate. The current status of RHIC EBIS and the results of the new gun development are presented.

Slides THO1AB03 [3.358 MB]

THO1AB04

Preserving Beam Quality in Long RFQs on the RF Side: Voltage Stabilization and Tuning

345

A. Palmieri
INFN/LNL, Legnaro (PD), Italy

RFQ’s are the injectors customarily used in modern linacs and the achievement of a high beam transmission for a RFQs is of paramount importance in case of both high intensity linacs and RIBs facilities. This calls for an accurate control of the longitudinal inter vane voltage along the four quadrants of the structure (field stabilization), in order to keep its deviation from nominal value as low as possible (a few %, typically). In particular, for long RFQ (in which the structure length can be significantly higher than the RF wavelength), this aspects is made more challenging, since the effect of a perturbations (e.g. due to mechanical errors and/or misalignments on the nominal RFQ geometry has a major impact on these voltage perturbations. In this presentation, an analysis of these aspects, as well as the methods used to tackle this problem will be described.

Slides THO1AB04 [3.244 MB]

Paper	Title	Page
THO1AB01	Simultaneous Acceleration of Radioactive and Stable Beams in the ATLAS Linac	334
	B. Mustapha, P.N. Ostroumov ANL, Argonne, USA M.A. Fraser CERN, Geneva, Switzerland A. Perry Illinois Institute of Technology, Chicago, Illlinois, USA
	Funding: This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics, under contract number DE-AC02-06CH11357. ATLAS is now the only US DOE National User Facility for low-energy heavy-ion stable beams. With the recent commissioning of the Californium Rare Isotope Breeder Upgrade (CARIBU), ATLAS is now also used to accelerate radioactive beams. The demand for both stable and radioactive beam time is already exceeding two to three times the 5500 hours delivered by ATLAS every year. The time structure of the EBIS charge breeder to be installed next year for CARIBU beams is such that only 3% of the ATLAS duty cycle will be used for radioactive beams. Being a CW machine, 97% of the ATLAS cycle will be available for the injection and acceleration of stable beams without retuning. This simultaneous acceleration is possible for stable and radioactive beams with charge-to-mass ratios within 3%. We have developed a strategic plan to upgrade ATLAS for this purpose over the next few years, where two to three beams could be delivered simultaneously to different experimental areas. The upgrade concept will be presented and discussed along with the recent studies and developments done in this direction.
	Slides THO1AB01 [1.829 MB]

THO1AB02	Experience with Stripping Heavy Ion Beams	340
	H. Okuno RIKEN Nishina Center, Wako, Japan
	Charge strippers play a critical role in many high intensity heavy ion accelerators. The recent progress on accelerator technology makes its role so critical that traditional carbon foils easily reach the limit of application due to their short lifetime. In fact the major heavy ion accelerator facilities such as GSI, MSU/ANL and RIKEN have made elaborating efforts to develop the alternatives to the carbon foils, in order to realize acceleration of very heavy ions such as uranium with high intensity. For example liquid lithium stripper has been developed at MSU/ANL and helium gas stripper and rotating Be disk stripper have been developed at RIKEN RIBF. The two strippers for RIBF greatly contributed to increase of the uranium beam intensity. However we are sure that Be disk stripper used for the second stripper will reach the limit in near future due to its large deformation, which require further developments for our intensity upgrade program.
	Slides THO1AB02 [11.042 MB]

THO1AB03	BNL Electron Beam Ion Sources: Status and Challenges
	A.I. Pikin, J.G. Alessi, E.N. Beebe BNL, Upton, Long Island, New York, USA R. Scrivens, A. Shornikov, F.J.C. Wenander CERN, Geneva, Switzerland
	Funding: US Department of Energy and the National Aeronautic and Space Administration The Electron Beam Ion Source (EBIS) at the Brookhaven National Laboratory (BNL) is a main source of highly charged ions for both Relativistic Heavy Ion Collider (RHIC) and NASA Space Radiation Laboratory (NSRL). It has delivered a wide variety of ions since 2010 with good stability and reliability. The ongoing development of the electron gun with electrostatic compression has a goal to significantly increase the current density of the electron beam. Such electron beam would allow boosting the charge state of ions, which RHIC EBIS injects into RFQ and therefore to increase their final energy at Booster for NSRL applications. This development can also benefit ISOLDE experiment at CERN, where high charge state of the extracted ions is as important as a large acceptance of EBIS and high repetition rate. The current status of RHIC EBIS and the results of the new gun development are presented.
	Slides THO1AB03 [3.358 MB]

THO1AB04	Preserving Beam Quality in Long RFQs on the RF Side: Voltage Stabilization and Tuning	345
	A. Palmieri INFN/LNL, Legnaro (PD), Italy
	RFQ’s are the injectors customarily used in modern linacs and the achievement of a high beam transmission for a RFQs is of paramount importance in case of both high intensity linacs and RIBs facilities. This calls for an accurate control of the longitudinal inter vane voltage along the four quadrants of the structure (field stabilization), in order to keep its deviation from nominal value as low as possible (a few %, typically). In particular, for long RFQ (in which the structure length can be significantly higher than the RF wavelength), this aspects is made more challenging, since the effect of a perturbations (e.g. due to mechanical errors and/or misalignments on the nominal RFQ geometry has a major impact on these voltage perturbations. In this presentation, an analysis of these aspects, as well as the methods used to tackle this problem will be described.
	Slides THO1AB04 [3.244 MB]