Gotta, D

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bore hole ofthe magnet is now shortened by a factor of 3.2. OCR Outputtheoretical limit of reflectivity and resolution. The read-out cycle of the CCD mounted in theetched to improve on the performence at the Lot energies, i.e. to approach closer to theIn 1995, upgraded CCDs and crystals are being installed. The Bragg crystal surfaces have beenshowing large e&`ects from Stark mixing even at the lowest pressure.The pressure dependence of the Balmer series has been measured from 1.3 to 30 mbarwas able to operate up to a rate of about 2·l0> incoming antiprotons per second.A 1 cmz CCD detector installed close to the stop volume in the bore hole of the magnetantiprotonic helium and neon.structure of the 2p levels is clearly seen when compared to the calibration lines fromThe broadening of the Lot transitions in hydrogen and deuterium due to the multipletclose to the limits as calculated from crystal diffraction theory have been achieved.With the spherically bent quartz and silicon crystals having a diameter of 10 cm, resolutionsobserved with the Bragg crystal spectrometer (fig. 1).Several hundreds of Lo. X-rays both from antiprotonic hydrogen and deuterium have beenthe crystal spectrometer to be $20 mm (FWHM) for 30 mbar hydrogen.The size ofthe X-ray source, i.e. the diameter of the stop volume, has been measured with30 mbar gas pressure.The incoming antiprotons were stopped to 90% in the center of the cyclotron trap atThe main results from the set-up measurement in 1994 are:of LEAR. For the iirst time, antiprotonic X-rays were observed with a crystal spectrometer.In a ilrst measuring period, experiment PS207 was set up and run using the 105 MeV/c beamx g z 5Patricia A5ZAMPAGLIONEZ[OT Afr Q.;1313_5 SPSLCAgg 5{/eRAiBeam-time rcqucst LEAR 1996From: PS207 collaborationSC0000O62195-67» CERN/SPSLC I mum SPSLC M 56 19.10.1995Memorandum to the S CERN LIBRARIES, GENEVA170 and 310 meV. OCR Outputand 360i40 meV were measured. The theoretical limits including geometrical broadening arecorresponding response functions ofthe apparatus. At 1.8 and 2.4 keV resolutions of 2301:30antiprotonic 4He and l3—>l2 of antiprotonic Ne, which are used to determine the20a sperically bent quartz and silicon crystal, respectively. Also shown are the transitions 5-+4 oftransitions of antiprotonic hydrogen and deuterium. The X-rays were reflected in first order byFig.1: Energy spectra of the CCD mounted on the crystal spectrometer showing the Lotchannelschannelsu zo no no no 100 120 no0 20 40 00 00 100 120 1401 •V,0 t` 1 •V¢|00$100R = Z.}! IIIR : 2.98 IIsph:.2.317 i•V1737 i•VSI III$013-2}quartz 100MI5 p I3 2)channelschannels0 20 I0 60 B0 100 120 1400 20 40 60 80 100 E0 140I •V5 }. I •V¢100QDOR r 2.98 InH : Mspher.1444 k•VIJII l•VSi 111qggrlg 109 Ez°NaI13-I2)EWIEI5-4)G.P. Latta and P.C. Tandy, Phys. Rev. C 42 (1990) Rl207 OCR OutputS. Wycech, A.M. Green, and J.A. Niskanen, Phys. Len. 52B (1985) 308the broadening, respectively.detectable in one week yielding an accuracy of about 10% and 30% for the hadronic shift andbroadening of 3 keV and a 2p level width of 300 meV, about 20000 Kon X-rays should bedeuterium should be feasible which is beyond the present detection limit. Assuming a linean energy of 12 keV. With such a detector, the observation of the Kot transition in antiprotonicIn addition, due to a depletion depth of 300 um the detection efficiency is about 80% even atincoming antrprotons.at 9 keV. About 2000 detected Kot X-rays from antiprotinic hydrogen are expected per l0the CCD presently used in the bore hole of the cyclotron trap. The energy resolution is 200 eVmeasurement of the Kot line shape. Such a device can be red out faster by a factor of 100 thanA fully depleted pn·CCD is being set up as a dedicated high-rate detector to improve on theDirect X—ray detection (‘Kot‘ measurement)It is plarmed to have a complete set of asymmetric cut crystals ready begimiing of 1996.of the data.So, an improvement on the resolution by a factor of 2.5 considerably improves the significancethe prediction for the ground state of Latta and Tandyz to the 2p level yields I`2D -·= 100 meV.calculation of Wycech, Green, and Niskanen (l`2D=400-500 meV)' . On the other hand, scalingindicating that at least some of the hyperfine transitions are narrower than expected from the0from our measurements in 1994 for the spin-averaged width of the 2p level is 26033meVpossible by changing from Si to asymmetric cut quartz crystals (tab. 1). The preliminary resultFor the case of the deuterium, a decrease of the rocking curve width by a factor of 2.5 issurfaces for all new crystals. (The duration ofthe full production cycle is about 6 months.)Furthermore, special etching procedures are applied to obtain very clean and homogenuousare being prepared in collaboration with the ZEISS company in Oberkochen, Germany.predicted by theory of crystal diffraction (tab. 1). At present, asymmetric cut quartz crystalsIn the case of the Lot transition in hydrogen, a decrease of the rocking curve width to 60% iscould be established for spherically bent asymmetric cut crystals (at an energy of 5.4 keV).Friedrich-Schiller-University at Jena, for the first time the reduction of the reflection widthof the mirror. In test experiments performed in collaboration with the ILL (Grenoble) and thecrystals. For asymmetric cut crystals, the reflecting planes have a finite angle with the surfaceThe resolution of the crystal spectrometer can be improved using asymmetric cut BraggCrystal spectrometer (‘Lot‘ measurement)detection of the Kot X-rays in the bore hole.both for the detection of the Lot transitions with the crystal spectrometer and the directFor the measurement ofthe hydrogen isotopes in 1996, new techniques are foreseen to be useddeuterium. OCR Outputthe total beam time from three to two weeks would require to choose between hydrogen anddeuterium measurement. (We assume 10antiprotons from LEAR per week.) A reduction of11are necessary surmning up to 1% weeks beam time for the hydrogen and 1 week for theTo achieve a suiiicient accuracy for the tits to the data, about 5000 events per Lo. transition0t=0° cx=38.2°270 50Si 111 80 | quartz 101 (100) | 110ot=0° cx=38.2°20quartz 100 | 148 35 |quartz 100 (101)] 87222Eaeaéiaéizisiz I t ·t(i·the simultanuous use of two crystals.iig. caption 1). The X·ray rate estimates per 109 incoming antiprotons (about 1 spill) are foris calculated by means of a Monte-Carlo ray-tracing code to be of the order of = 15% (seetheory for flat crystals. For curved crystals, an additional geometrical broadening occurs, whichreflecting plane. AE is the width of the crystal rocking curve as calculated from diffractionThe cut angle ot is the angle between the crystal surface (Miller indices in parenthesis) and theTable 1: Comparison of the symmetric and the asymmetric Bragg case.1.85 keV) is fully covered by the detector.possible. That means, that the energy range of the M series of antiprotonic deuterium (0.81Because the pn-CCD is illuminated Gem the rear, the detection of X-rays down to 0.7keV isD. GottaFor the PS207 collaborationChanging the set-up from hydrogen to deuterium takes 6-12 hours.8 days OCR Output• deuterium• hydrogen 10 daysset-up of crystal spectrometer 2 days• beam line Sct-up, optimization of injection into the cyclotron trap, andSchedule foreseen for a measuring period of 3 weeks:• beam time request: 3 weeks main user• spill duration of 20 min for the measurement with the crystal spectrometer• main user at maximum intensity ( 2109 incoming antiprotons per spill)• beam momentum 105 MeV/c• set-up in area S3 at LEARSet·up parameters:deuterium using the new techniques described abvove.The PS207 collaboration asks for beam time in 1996 to measure antiprotonic hydrogen andBEAM PARAMETERS and BEAM TIME REQUEST for 1996

Beam-time request LEAR 1996

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