Nuclear Instruments and Methods in Physics Research A282 (1989) 191-193North-Holland, Amsterdam

RECENT DEVELOPMENTS IN THE TARGET FACILITIES AT ARGONNENATIONAL LABORATORY

John P. GREENE and George E. THOMAS

Physics Division, Argonne National Laboratory, 9700 S. Cass Avenue, Argonne, IL 60439, USA

A description is given of recent developments in the target facility at Argonne National Laboratory (ANL). Highlights includeequipment upgrades which enable us to provide enhanced capabilities for support of the Argonne Heavy-Ion ATLAS AcceleratorProject . Also, future plans and additional equipment acquisitions will be discussed.

1. Introduction

The Argonne Physics Division Target FabricationFacility provides thin films for atomic and nuclearphysics experiments as well as for other scientific pro-jects. The great majority of targets produced are forexperiments at the Argonne Tandem Linac AcceleratorSystem (ATLAS) facility which, since its commissioningas a National Users Facility in 1985, has placed increas-ing demands on the targets required . In this paper, theexisting capabilities and plans for meeting these require-ments will be discussed.

Table 1Resistively heated targets produced

0168-9002/89/$03 .50 © Elsevier Science Publishers B.V.(North-Holland Physics Publishing Division)

2. Physics Division Target Laboratory

The Target Fabrication Facility consists of a varietyof equipment. Capabilities include apparatus for resis-tive and electron beam gun evaporation and for thinfilms produced using sputtering techniques. Auxiliaryequipment provides support for the numerous otheractivities required for target fabrication .

2.1 . Vacuum evaporators

The Target Laboratory maintains four evaporationsystems, each of which is described below along with itscapabilities for the production of targets .

VI . ACTIVITY REPORTS

Self-supporting On various substrates

Target Thickness Target Thickness Substrate Thickness(Wg/cm2 ) (Wg/cm2) (Wg/cm2 )

24,26Mg 60-100 28 S'02 60 Ta (0.5 mm sheet)AI 20-30 Ca 70-200 C 2058,64Ni 200 46TiO2 120-300 Pb 22Ag 20-40 60Ni 100-200 C 10-14119,120,122 Sn 300-400 74,76Ge 50-1000 Au 1000125Te 300-500 94Mo 180-230 C 22Au 50-70 119,120,122,124Sn 10-500 C 2-500

122Te 1000 Au 1000138 Ba 100-200 C 30-60Hf 150-200 C 20186W03 200 C 20Au 10-15 Cu 2-4208 Pb 100 C 15-20PbF2 200 C 600Bi 200 C 20144,150,154Sm 275-400 C 20160Gd 15-100 C 4-15Tb 10-15 C 2-4Er 150 C 15Lu 203 100-135 C 20-40Teflon PTFE 45-100 C 600Teflon TFE 45-100 C 600

192

Table 2Targets produced by electron-beam evaporation10,1113

C9aMo

J.P. Greene, G.E Thomas / Target facilities at Argonne National Laboratory

100-200 Wg/cmz (self-supporting)(self-supporting and for coverings)30-200 wg/CMZ (carbon substrates)

A NRC 3117 evaporator system with a Varian oildiffusion pump and large-capacitance liquid nitrogencold trap is our primary apparatus for either single ormultiple resistively evaporated targets. Included withinthis apparatus is a Veeco Model VeB-6 electron beamgun system . Maier-Komor's [1] review paper on electronbeam gun evaporation discusses some of the character-istics of this system. Tables 1 and 2 list examples oftargets manufactured in this system by either resistanceor electron beam evaporation .A second system, a Veeco Model VE-775 vacuum

evaporator, also employs a Varian oil diffusion pumpwith cold trap . This secondary system is also capable ofmultiple resistive evaporations. The apparatus is prim-arily used for "quick" evaporations, such as salt sub-strates, to be subsequently used for isotopically puretargets along with routinely producing gold foils ofvarious thicknesses. This apparatus has also been con-sistently made available to visitors and students forspecial projects (e .g ., production of calcium pellets bycalcium oxide reduction for use in the accelerator ionsource) .A third evaporator is an ultraclean system pumped

by an Air Products model CSW-202 cryopump . Withinthis apparatus is installed an Ion Tech saddle-fieldsputter source Model Fab 11N . A modified source ofthis design is described in detail by Muggleton [2] .Targets of various thicknesses (on framed carbon foils)produced using this sputter gun are, e .g ., Ti, V, Cr, Zr,W, and Pt .

The above three systems are each equipped withKronos Model QM-331 quartz crystal thickness gaugesfor monitoring vapor deposition and with thermocoupletemperature sensors. These devices enable us to monitora number of aspects of quality control in target produc-tion .

The last vacuum evaporation system to be describedis a glow discharge apparatus. This piece of equipmenthas only recently been moved into our laboratory. It ispumped using a Sargent-Welch Turb-Torr Model 3133turbo-molecular pump and employs a MRC high-volt-age 5-kV do supply to produce an argon plasma. In thepast, it had been used to crack ethylene for the produc-tion of stripper foils [3] . Recently, we have employed itfor cleaning critical surfaces, especially glass cells usedfor an experiment involving a polarized deuterium target.

All of the above evaporators are kept under highvacuum (10 -6 Pa) and are monitored using Bayard-Al-

pert tubulated ion gauges and Granville-Phillips series270 ionization gauge controllers. During deposition,pressures of = 8 X 10-5 Pa can usually be maintained .

2.2. Auxiliary equipment

In addition to our vacuum evaporation systems, thetarget laboratory has a significant complement of aux-iliary equipment to support our target making capabili-ties . Among them include a Frei & Borel type SE/EXrolling mill. The laboratory also has a Lindberg Furnaceequipped with a gas manifold for use in hydrogenreductions . It has been used for specific chemical reac-tions under inert gas flow as well as for vacuum anneal-ing . A recently procured Forma Scientific Model 1854laminar flow hood has provided us with additionalbench space for floating difficult (thin) targets. An inertgas glove box (also of Forma Scientific) was recentlymade available for our use and has been employed inthe production of targets which may oxidize quickly.We also have a full complement of precision balances,including Mettler analytical and microbalances alongwith a Cahn Model 4400 electrobalance .

2.3. Target storage facilities

The target Laboratory employs three vacuum sys-tems for the storage of fragile or vulnerable foils . Thefirst is a highly automated vacuum storage device devel-oped at Argonne [4,5] . It consists of a turbo-pumpedchamber enclosing a rotating carrousel capable of hold-ing up to 100 standard target frames . It is kept undervacuum (10 -5 Pa) by active computer control (i .e., aftera power shut-down, it will pump down to vacuumautomatically, thereby maintaining the integrity of thetargets stored within it) . A second, quite similar systemhas been recently constructed although not under com-puter control . This chamber will be used for routinestorage of hydroscopic and slowly oxidizing targets forextended periods of time relieving the burden of targetstorage within our vacuum desiccators . With targetsnow being stored in the second storage system, the useof vacuum desiccators for storage of oxidizing materialsand foils can increase .

2 .4 . Laboratory personal computer

Available in the laboratory is an IBM PC/XT com-puter currently running DOS version 2 .1 . Besides thecomputer system with its two floppy disk drives, there isan enhanced graphic 5154 color monitor and letterquality IBM printer . Extensive use has been made ofthis system for chemical and stable isotope inventoriesand for establishing a record, with cross-references, ofall targets manufactured since 1978 . In addition, thereare programs used to generate labels for identification

J.P. Greene, G.E. Thomas / Target facilities at Argonne National Laboratory

of targets, evaporation boats, and source compounds .Further integration of this computer into laboratoryfunctions is intended in the near future .

3 . Prospects for the future

A new acquisition and two major projects have takenplace within the target laboratory recently which shouldsignificantly enhance our capabilities for producinghigh-quality targets .

The purchase of a Temescal Model STIH-270-1four-pocket turret electron beam source will enable usto now perform multiple electron beam evaporations.

Equipment has been made available for the develop-ment of a laboratory for the production of low-levelradioactive targets . Equipment will include a dedicatedvacuum evaporator, microbalance, etc. It is anticipatedthat this facility will be used for the manufacture oftargets necessary to support Argonne's ATLAS programupon completion of the new ECR Source, which willextend its capabilities up to uranium beams .A mass isotope separator was recently acquired and

transported to the Physics Division from the ANLChemistry Division. This device should be put intooperation for the production of targets in the nearfuture .

Acknowledgements

We would like to thank the following persons fortheir hard work, help, encouragement, and support :James Douglass, Bonnie Pewett, and the Physics Divi-sion Support Group . This work was supported by theU.S . Department of Energy, Nuclear Physics Division,under contract W-31-109-ENG-38 .

References

P . Maier-Komor, Proc . 4th Ann. Conf. of the NuclearTarget Development Society, Argonne National Labora-tory, Argonne, IL, 1975 (ANL/PHY/MSD-76-1) p . 207.A.H.F . Muggleton, Research School of Physical Sciences,The Australian National University (ANU-P/965 July1987) .G.E . Thomas, P.K . Den Hartog, J.J . Bicek and J.L. Yntema,Proc . 6th Ann . Conf. of the Int. Nuclear Target Develop-ment Society, Lawrence Berkeley Laboratory, Berkeley,CA, 1977 (LBL-7950, UC-34c, 1978) p . 17 .

[4] B.G . Nardi and J.N. Worthington, Proc. Workshop 1983,Int. Nuclear Target Development Society, Argonne Na-tional Laboratory, Argonne, IL (ANL/PHY-84-2) p . 153 .G.W. Klimczak, B.G . Nardi and D.J . Travis, Nucl. Instr.and Meth . A257 (1987) 57 .

193

VI . ACTIVITY REPORTS