A beam of six-charged carbon ions with an energy of 24.8 GeV/nucleon is extracted from the U-70 synchrotron by means of a silicon crystal bent through 85 mrad. A total of 200000 particles are observed in beamline 4a upon forcing 109 circulating ions to the crysta

Afonin, A. G.

Barnov, E. V.

Britvich, G. I.

Durum, A. A.

Kubankin, A. S.

DSpace at Belgorod State University

497ISSN 0020-4412, Instruments and Experimental Techniques, 2016, Vol. 59, No. 4, pp. 497–500. © Pleiades Publishing, Ltd., 2016.Original Russian Text © A.G. Afonin, E.V. Barnov, G.I. Britvich, A.A. Durum, M.Yu. Kostin, V.A. Maisheev, V.I. Pitalev, S.F. Reshetnikov, Yu.A. Chesnokov, P.N. Chirkov,A.A. Yanovich, R.M. Nazhmudinov, A.S. Kubankin, A.V. Shchagin, 2016, published in Pribory i Tekhnika Eksperimenta, 2016, No. 4, pp. 16–19.Extraction of the Carbon Ion Beam from the U-70 Acceleratorinto Beamline 4a Using a Bent Single CrystalA. G. Afonina, E. V. Barnova, G. I. Britvicha, A. A. Duruma, M. Yu. Kostina, V. A. Maisheeva,V. I. Pitaleva, S. F. Reshetnikova, Yu. A. Chesnokova*, P. N. Chirkova, A. A. Yanovicha,R. M. Nazhmudinovb, A. S. Kubankinb, and A. V. Shchaginb, ca Institute for High Energy Physics, National Research Centre Kurchatov Institute,pl. Nauki 1, Protvino, Moscow oblast, 142281 Russiab Belgorod State University, Belgorod, 308015 Russiac Kharkiv Institute of Physics and Technology, Kharkiv, 61108 Ukraine*e-mail: chesnokov@ihep.ruReceived July 31, 2015Abstract—A beam of six-charged carbon ions with an energy of 24.8 GeV/nucleon is extracted from the U-70synchrotron by means of a silicon crystal bent through 85 mrad. A total of 200000 particles are observed inbeamline 4a upon forcing 109 circulating ions to the crystal. The geometrical parameters, timing structure,and composition of the beam have been measured. It has been shown for the first time that, using a bent singlecrystal, an ion beam with required parameters can be extracted from the accelerator ring and formed for reg-ular use in physics experiments.DOI: 10.1134/S002044121603012XBent single crystals have long been used to goodeffect to extract proton beams from accelerators, inparticular, from large modern colliders [1–3]. The useof single crystals for extracting a portion of the protonbeam with energies of 50–70 GeV into various beam-lines has become customary practice at the Institutefor High Energy Physics (IHEP) [4, 5]. Carbon ions,along with protons, have been accelerated lately at theU-70 synchrotron [6]. The mode of extraction of thesix-charged carbon ion beam with an energy of24.8 GeV/nucleon into beamline 4a was investigatedin the U-70 run in the spring of 2015. It should benoted that the possibility of using crystals for deflect-ing and extracting ion beams was demonstrated about20 years ago [7, 8], and collimation of heavy ions onthe circulating beams of the RHIC and SPS accelera-tors was investigated in later experiments [9, 10].The purpose of this work was to produce and studya stable ion beam with the aid of particle extraction bya crystal for use in regular U-70 runs.The layout of carbon ion beam extraction by meansof a crystal deflector and its transport in beamline 4ais shown in Fig. 1.The crystal deflector CD was installed in the vac-uum goniometer inside the 27th magnetic unit of theU-70. The oblong silicon crystal wafer with orienta-tion (111) and dimensions of 0.3 × 3 × 60 mm (thick-ness, height, and length downstream of the beam) wasbent through an angle of 85 mrad with the aid of ametal holder (Fig. 2). The bending angle as large asthis is explained by the specific features of beamline4a. Nominally, it is used to obtain negative particles onthe internal amorphous target of the U-70 accelerator.Negative particles are ejected by the magnetic field ofthe accelerator into the outer side of the ring, whereasprotons or ions deflected by the crystal are turnedinward.Bump magnets were used for forcing the circulatingbeam onto the crystal. Two bending magnets М1 andМ2 ejected the beam that had been channeled anddeflected by the crystal into beamline 4a and thereaf-ter was formed by two quadrupole lenses HL and VL.Beam collimators HC and VC were fully opened. TheNUCLEAR EXPERIMENTALTECHNIQUEFig. 1. Diagram of carbon ion beam extraction into beam-line 4a: (CD) crystal deflector, (M1, M2) deflecting mag-nets, (HC, VC) horizontal and vertical collimators (HL,VL) horizontal and vertical quadrupole lenses, (C1, C2, C3)scintillation counters, and (SD) semiconductor detector.U-70 orbitSDVLHLVCCDHCM2M1C1C2C3С+6~100 m40 mrad85 mrad498INSTRUMENTS AND EXPERIMENTAL TECHNIQUES  Vol. 59  No. 4  2016AFONIN et al.beam intensity was measured by large scintillationcounters C1 and C2.A direct proof that the extracted beam is channeledconsists in the so-called orientation curve—thedependence of the extracted beam intensity on thecrystal angle with respect to the incident beam direc-tion. The results of the angular scanning of the beamby the crystal are shown in Fig. 3.At a maximum, (2.2 ± 0.3) × 105 particles wereobserved in beamline 4a when 109 ions were incidenton the crystal deflector. Full width at half-maximumof the curve σ = 0.2 mrad corresponds to the angularbeam spread in the accelerator. The obtained beamextraction efficiency complies with the theoreticalexpectations.In Fig. 4, the theoretical point (an asterisk) for car-bon fits the theoretical curve well [11]. The figure alsopresents the theoretical curve and experimental pointsFig. 2. Design of the crystal deflector with a bending angleof 85 mrad.Beam1 cmFig. 3. Number of particles in the beamline vs. crystal ori-entation φ with respect to the beam direction.1002000500 0 500 ϕ, mradEvents, 103Fig. 4. Efficiency of carbon (C) and proton (p) circulatingbeam extraction by crystals as a function of the bendingangle. The calculation results are shown with curves, thesolid circles present the experimental values for protons,and the asterisk is the experimental value for carbon.*EfficiencyCpAngle, mrad10010110210310440 80 120 1600Fig. 5. Timing structure of the ion beam incident on thecrystal, which was measured by monitors 1 and 2.0 40 80 120 160 200Time, msBeam intensity12INSTRUMENTS AND EXPERIMENTAL TECHNIQUES  Vol. 59  No. 4  2016EXTRACTION OF THE CARBON ION BEAM FROM THE U-70 ACCELERATOR 499for the proton beam [11]. The efficiency of beamextraction by the crystal was calculated using theSCRAPER program [12]. Both particle passagethrough the crystal in view of nuclear interactions andmultiturn movement in the U-70 accelerator weretaken into account in the calculation. It should benoted that the extraction efficiency for carbon ions isseveral times lower than the respective value for theproton beam, though the channeling properties ofcrystals are identical for ions with equal values of themagnetic rigidity (the ratio of the particle momentumto its charge p/z), which was established in [7, 8].The lower (relative to protons) extraction and collima-tion efficiency for the circulating ion beam was alsoobserved in [8–10]. It is explained by the higher-intensity nuclear interaction of ions with the crystal-line target in comparison with protons in multiturnparticle movement in the accelerator.The signals from the scintillation monitors of beamguidance toward the crystal in the accelerator aredepicted in Fig. 5. Analysis of the signals shows thatthe uniformity of guidance and the timing structure ofthe beam are good, though the intensity of circulatingparticles is low.Figure 6 presents the image of the extracted beamat the site of the detectors, which was obtained usingthe EVT3 radiation monitoring film. The full width athalf-maximum of the carbon ion beam is ~10 mm inboth planes. This corresponds to the size of the protonbeam extracted earlier.The beam composition was measured at its centerby the ionization loss in thin scintillator C3. The resultsare shown in Fig. 7. Ions with different charges wereidentified by the quadratic dependence of the ioniza-tion loss. It is apparent that the carbon peak with acharge STATE of 6 dominates (~80%). At the beamperiphery, i.e., at a level of 1% of the main intensity,the beam composition was measured with semicon-ductor surface-barrier detector SD (the detector posi-tion with reference to the beam center is shown with asquare in Fig. 6).The spectra of ionization losses on the detector arepresented in Fig. 8. One can see that there are 30% ofcarbon and numerous fragments. The presence ofthese fragments is mainly caused by interactions of theFig. 6. Image of the particle distribution in the extractedbeam.0.0250.0200.0150.0100.005010203040506070809010 20 30 40 50 60 70 800Y, mmX, mmFig. 7. Ionization loss spectra of beam particles in scintil-lator С3.50100150200250300200 400 600 800 1000Z = 2Z = 6Z = 30ChannelsEventsFig. 8. Ionization loss spectra of beam particles in thesemiconductor (the black line is in the linear scale and thegray line is in the logarithmic scale).Z = 1Z = 2Z = 3Z = 4 Z = 5Z = 65001000150020001011021031041001000 2000 3000 4000 50000Energy, keVEvents Events500INSTRUMENTS AND EXPERIMENTAL TECHNIQUES  Vol. 59  No. 4  2016AFONIN et al.extracted carbon beam with vacuum-tight partitionsand other substances in beamline 4a (~5 g/cm2).As a result, the investigation has shown that, usinga bent single crystal, it is possible to extract an ionbeam from the accelerator with acceptable parameters(beam intensity, timing structure, and composition)for physics experiments scheduled for regular runs ofthe U-70 accelerator.REFERENCES1. Afonin, A.G., Baranov, V.T., Biryukov, V.M.,Breese, M.B.H., Chepegin, V.N., Chesnokov, Yu.A.,Guidi, V., Ivanov, Yu.M., Kotov, V.I., Martinelli, G.,Scandale, W., Stefancich, M., Terekhov, V.I., Trboje-vic, D., Troyanov, E.F., and Vincenzi, D., Phys. Rev.Lett., 2001, vol. 87, no. 9, p. 094802.  doi 10.1103/Phys-RevLett.87.0948022. Scandale, W., Arduini, G., Assmann, R., Bracco, C.,Gilardoni, S., Ippolito, V., Laface, E., Losito, R.,Masi, A., Metral, E., Previtali, V., Redaelli, S., Silari, M.,Tlustos, L., Bagli, E., et al., Phys. Lett., B, 2010,vol. 692, no. 2, p. 78. doi 10.1016/j.physletb.2010.07.0233. Shiltsev, V., Annala, G., Drozhdin, A., Johnson, T.,Legan, A., Mokhov, N., Reilly, R., Still, D., Tesarek, R.,Zagel, J., Peggs, S., Assmann R., Previtali V., Scandale W.,Chesnokov Y., et al., IPAC-2010-TUOAMH03. FER-MILAB-CONF-10-127-APC, 2010. Arxiv: 1202.15194. Asseev, A.A., Bavizhev, M.D., Lyudmirsky, E.A.,Maisheev, V.A., and Fedotov, Yu.S., Nucl. Instrum.Methods Phys. Res., Sect. A: Acceler., Spectrom., Detect.Assoc. Equip., 1991, vol. 309, nos. 1–2, p. 1.5. Chesnokov, Yu.A., Afonin, A.G., Baranov, V.T., Brit-vich, G.I., Chirkov, P.N., Maisheev, V.A., Terekhov, V.I.,and Yazynin, I.A., Nucl. Instrum. Methods Phys. Res.,Sect. B: Beam Inter. Mater. Atoms, 2013, vol. 309, p. 105.doi 10.1016/j.nimb.2013.03.0156. Ivanov, S.V., in Proc. RUPAC 2012. Saint-Petersburg,Russia, 2012, p. 120. http://accelconf.web.cern.ch/AccelConf/rupac2012/papers/wecch01.pdf7. Bel’zer, L.I., Bodyagin, V.A., Vardanyan, I.N., Gri-bushin, A.M., Ershov, A.A., Zharkov, N.A., Kirillov, A.D.,Kodolova, O.L., Komolov, L.N., Kukushkina, R.I.,Rukoyatkin, P.A., Sarycheva, L.I., Svetov, A.L.,Semenyushkin, I.N., and Sinev, N.B., JETP Lett.,1988, vol. 46, no. 8, p. 381.8. Arduini, G., Biino, C., Clement, M., Cornelis, K.,Doble, N., Elsener, K., Ferioli, G., Fidecaro, G.,Gatignon, L., Grafstrom, P., Gyr, M., Herr, W., Klem, J.,Uggerhoj, U.I., Weisse, E., et al., Phys. Rev. Lett., 1997,vol. 79, p. 4183.9. Fliller, R.P., Drees, A., Gassner, D., Hammons, L.,McIntyre, G., Peggs, S.G., Trbojevic, D., Biryukov, V.,Chesnokov, Y., and Terekhov, V., Phys. Rev. ST Accel.Beams, 2006, vol. 9. p. 013501. DOI:  doi 10.1103/Phys-RevSTAB.9.01350110. Scandale, W., Arduini, G., Assmann, R., Bracco, C.,Cerutti, F., Christiansen, J., Gilardoni, S., Laface, E.,Losito, R., Masi, A., Metral, E., Mirarchi, D., Monte-sano, S., Previtali, V., Redaelli, S., et al., Phys. Lett., B,2011, vol. 703, p. 547. doi 10.1016/j.physletb.2011.08.023411. Arkhipenko, A.A., Afonin, A.G., Baranov, V.T., Brit-vich, G.I., Kotov, V.I., Maisheev, V.A., Maksimov, A.V.,Reshetnikov, S.F., Chepegin, V.N., Chesnokov Yu.A.,and Yazynin, I.A., JETP Lett. 2008, vol. 88, no. 4,p. 229.  doi 10.1134/S002136400816001712. Degtyarev, I., Liashenko, O.A., and Yazynin, I.A., inProc. PAC 2001, Chicago, p. 2506. http://accelconf.web.cern.ch/AccelConf/p01/PAPERS/ WPPH314.PDFTranslated by N. Goryacheva

Extraction of the carbon ion beam from the U-70 accelerator into beamline 4a using a bent single crystal

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Extraction of the carbon ion beam from the U-70 accelerator into beamline 4a using a bent single crystal

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