Braunroth, T.

Dewald, A.

Ellinger, E.

Fransen, C.

Litzinger, J.

Wölk, D.

GSI Repository

A plunger for high energy beams to be used at HISPEC/ PRESPECC. Fransen1, T. Braunroth1, A. Dewald1, E. Ellinger1, J. Litzinger1, and D. Wo¨lk11IKP, Cologne, GermanyFigure 1: Left: Plunger device with ﬂat springs. Right:Plunger device with three motors.Development of a plunger for high energy beams tobe used at HISPEC/ PRESPECA plunger for high energy beams to be used at the HISPEC/PRESPEC set-up at GSI Helmholtzzentrum fu¨r Schwerio-nenforschung is under construction in Cologne.There are special challenges for plunger measurementswith relativistic beams.• The distances between the target and the degraderfoils have to be variable in a range from mechanicalcontact up to a few centimeters because of the highrecoil velocities of the order of v/c = 50%.• The target and degrader foils need to be large enoughfor a typical beam diameter up to 8 cm and the struc-ture has to be sufﬁciently stable to allow an accurateand parallel mounting of target and degrader foils withthicknesses in the range of a few μm for foils up tomore than 1 mm.These are different dimensions compared to a standardplunger device for fusion evaporation reactions, where thefoils have thicknesses in the order of micrometers and thebeam diameter is typically around one millimeter.Two different types of devices have been constructed andtested in Cologne, as described in the following passages.A plunger with ﬂat springsFor the exact movement of such extremly large andheavy target foils another plunger concept than usual isnecessary. A plunger device with ﬂat springs allow for aparallel movement of target and degrader with respect toeach other. A prototype for testing was built (see Figure1). It has a maximum driving range of 30 mm, limited bythe piezo motor, and a precision of 0.1 mm. Thus this is aconstruction for experiments where a rather low precisionis needed.Figure 2: Experimental setup for measuments for RDDSexperiments with extremly large beam diameters.A plunger with three motorsA precision of 0.1 mm is not sufﬁcient for all plungermeasurements with low energetic beams. Therefore, theconstruction of a second plunger device with three piezomotors is in progress. A prototype for testing was built(see Figure 1 right-hand side). We proved that by using anew software developed at IKP, Cologne three Piezo mo-tors can be operated parallel in a way to achieve a highlyprecise parallelism of target and degrader foil. It has beenfound, that this plunger fulﬁlls all requirements of a fu-ture experiment to be performed at the HISPEC/ DESPEC/AGATA experimental set-up. It is also possible to constructthis plunger in a three foil version.Experimental setup to test RDDS experimentswith extremly large target and stopper/ degraderfoilsA setup to test RDDS experiments with extremly largetarget and degrader/stopper foils is shown in Fig. 2. It is in-tended to excite levels in Ta via Coulomb excitation wherelifetimes are very well known [1]. By this method it will bepossible to measure absolute target to stopper seperationsat different locations on the target. Separate sets of pho-todiodes will be used to measure backscattered projectilesat the speciﬁc target locations (xi, yi) to ﬁx the kinematicsof the coulomb excitations. This experiment will be per-formed at the Cologne FN tandem accelerator.References[1] T. Klug, A. Dewald, V. Werner, P. von Brentano, R.F. Casten,Phys. Lett. B 495 (2000) 55.PHN-ENNA-EXP-52 GSI SCIENTIFIC REPORT 2012182

A plunger for high energy beams to be used at  HISPEC/PRESPEC

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A plunger for high energy beams to be used at HISPEC/PRESPEC

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