hep-ph/ v2 25 Nov 1999

Transcription

1 DESY ISSN AU-HEP-99/02 he-h/ October 1999 The ost-hera era: brief review of future leton-hadron and hoton-hadron colliders he-h/ v2 25 Nov 1999 Abstract S. Sultansoy Deutsches Elektronen-Synchrotron DESY, Hamburg, Germany Deartment of Physics, Faculty of Sciences, Ankara University, Turkey Institute of Physics, Academy of Sciences, Baku, Azerbaijan Otions for future l, la, γ, γa and FEL γa colliders are discussed. 1

2 CONTENTS 1. INTRODUCTION 2. FIRST STAGE: TESLA HERA, LEP LHC and µ ring TEVATRON 2.1. TESLA HERA comlex i) e otion ii) γ otion iii) ea otion iv) γa otion v) FEL γa otion 2.2. LEP LHC i) e otion ii) ea otion 2.3. µ ring TEVATRON 3. SECOND STAGE: Linac LHC and s=3 TeV µ 3.1. Linac LHC i) e otion ii) γ otion iii) ea otion iv) γa otion v) FEL γa otion 3.2. s=3 TeV µ 4. THIRD STAGE: e ring VLHC, LSC ELOISATRON and multi-tev µ 4.1. e ring VLHC 4.2. LSC ELOISATRON 4.3. Multi-TeV µ 5. CONCLUSION 2

3 1. Introduction It is known that leton-hadron collisions have been laying a crucial role in exloration of dee inside of Matter. For examle, the quark-arton model was originated from investigation of electron-nucleon scattering. HERA has oened a new era in this field extending the kinematics region by two orders both in high Q 2 and small x comared to fixed target exeriments. However, the region of sufficiently small x and simultaneously high Q 2 ( 10 GeV 2 ), where saturation of arton densities should manifest itself, is currently not achievable. It seems ossible that ea otion of HERA will give oortunity to observe such henomena. Then, the acceleration of olarized rotons in HERA could rovide clear information on nucleon sin origin. The investigation of hysics henomena at extreme small x but sufficiently high Q 2 is very imortant for understanding the nature of strong interactions at all levels from nucleus to artons. At the same time, the results from leton-hadron colliders are necessary for adequate interretation of hysics at future hadron colliders. Today, linacring tye e machines seem to be the main way to TeV scale in leton-hadron collisions; however, it is ossible that in future µ machines can be added deending on solutions of rincial issues of basic µ + µ colliders. The aim of this brief review is to draw the attention of the HEP community to these facilities. 2. First stage: TESLA HERA, LEP LHC and µ ring TEVATRON 2.1. TESLA HERA comlex Construction of future leton linacs tangentially to hadron rings (HERA, Tevatron or LHC) will rovide a number of additional oortunities to investigate leton-hadron and hoton-hadron interactions at TeV scale (see [1-3] and references therein). For examle: TESLA HERA = TESLA HERA TeV scale e collider TeV scale γ collider ea collider γa collider FEL γa collider. The future otions to collide electron and hoton beams from TESLA with roton and nucleus beams in HERA were taken into account by choosing the direction of TESLA tangential to HERA [4-6]. It should be noted that γ and γa otions are unique features of linac-ring tye machines and can not be realized at LEP LHC, which is comarable with TESLA HERA e and ea otions. i) e otion [7-10] There are a number of reasons favoring a suerconducting linear collider (TESLA) as a source of e-beam for linac-ring colliders. First of all sacing between bunches in warm linacs, which is of the order of ns (see Table I) [11], doesn t match with the bunch sacing in the HERA, TEVATRON and LHC (see Table II) [12]. Also the ulse length is 3

4 much shorter than the ring circumference. In the case of TESLA, which use standing wave cavities, one can use both shoulders in order to double electron beam energy, whereas in the case of conventional linear colliders one can use only half of the machine, because the travelling wave structures can accelerate only in one direction. The most transarent exression for the luminosity of this collider is [8]: 1 P n γ e Le = N 4π Ee ε β for round, transversely matched beams. Using the values of ugraded arameters of TESLA electron beam from Table III and HERA roton beam from Table IV, we obtain L e = cm -2 s -1 for E e =300 GeV otion. The lower limit on β, which is given by roton bunch length, can be overcome by alying a dynamic focusing scheme [9], where the roton bunch waist travels with electron bunch during collision. In this scheme β is limited, in rincile, by the electron bunch length, which is two orders magnitude smaller. More conservatively, an ugrade of the luminosity by a factor 3-4 may be ossible. Therefore, luminosity values exceeding cm -2 s -1 seems to be achievable for all three otions given in Table III. Further increasing of luminosity can be achieved by increasing the number of rotons in bunch and/or decreasing of normalized emittance. This requires the alication of effective cooling methods at injector stages. Moreover, cooling in the HERA ring may be necessary in order to comensate emittance growth due to intra-beam scattering [10]. First studies of the beam otics in the interaction region are resented in [7] and [9], where head-on collisions are assumed. The basic concet consists of common focusing elements for both the electron and the roton beams and searating the beams outside of the low-beta insertion. However, collisions with small crossing angle ( 100 µrad) are also a matter of interest, esecially for γ and γa otions (see below). Further work on the subject, including the detector asects, is very imortant. In rincile, TESLA HERA based e collider will extend the HERA kinematics region by an order in both Q 2 and x and, therefore, the arton saturation regime can be achieved. A brief account of some SM hysics toics (structure functions, hadronic final states, high Q 2 region etc.) is resented in [13], where a ossible ugrade of the H1 detector is considered. The BSM search caacity of the machine will be defined by future results from LHC. If the first family letoquarks and/or letogluons have masses less than 1 TeV they will be roduced coiously (for coulings of order of α em ). The indirect manifestation of new gauge bosons may also be a matter of interest. In general, the hysics search rogram of the machine is a direct extension of the HERA search rogram. ii) γ otion [14-16] Earlier, the idea of using high energy hoton beams obtained by Comton backscattering of laser light off a beam of high energy electrons was considered for γe and γγ colliders (see [17] and references therein). Then the same method was roosed in [14] for constructing γ colliders on the base of linac-ring tye e machines. Rough estimations of the main arameters of γ collisions are given in [15]. The deendence of these arameters on the distance z between conversion region and collision oint was analyzed in [16], where some design roblems were considered. 4

5 Referring for details to [16] let me note that L γ = cm -2 s -1 at z=10 cm for TESLA HERA based γ collider with 300 GeV energy electrons beam. Then, the luminosity slowly decreases with the increasing z (factor ~1/2 at z=10 m) and oosite helicity values for laser and electron beams are advantageous. Additionally, a better monochromatization of high-energy hotons seen by roton bunch can be achieved by increasing the distance z. Finally, let me remind you that an ugrade of the luminosity by a factor 3-4 may be ossible by alying a dynamic focusing scheme. The scheme with non-zero crossing angle and electron beam deflection considered in [16] for γ otion lead to roblems due to intensive synchrotron radiation of bending electrons and necessity to avoid the assing of electron beam from the roton beam focusing quadruoles. Alternatively, one can assume head-on-collisions (see above) and exclude deflection of electrons after conversion. In this case residual electron beam will collide with roton beam together with high-energy γ beam, but because of larger crosssection of γ interaction the background resulting from e collisions may be neglected. The roblem of over-focussing of the electron beam by the strong roton-low-β quadruoles is solved using the fact of smallness of the emittance of the TESLA electron beam. For this reason the divergence of the electron beam after conversion will be dominated by the kinematics of the Comton backscattering. In the case of 300 (800) GeV electron beam the maximum value of scattering angle is 4 (1.5) micro-radians. Therefore, the electron beam transverse size will be 100 (37.5) µm at the distance of 25 m from conversion region and the focusing quadruoles for roton beam have negligible influence on the residual electrons. On the other hand, in the scheme with deflection there is no restriction on n e from Q, therefore, larger n e and bunch sacing may be referable. All these toics need a further research. Concerning the exerimental asects, very forward detector in γ-beam direction will be very useful for investigation of small x g region due to registration of charmed and beauty hadrons roduced via γg Q Q sub-rocess. There are a number of aers (see [3] and refs. therein), devoted to hysics at γ colliders. Concerning the BSM hysics, γ otion of TESLA HERA doesn t romise essential results with ossible exclusions of the first family excited quarks (if their masses are less than 1 TeV) and associate roduction of gaugino and first family squarks (if the sum of their masses are less than 0.5 TeV). The hoto-roduction of W and Z bosons may be also the matter of interest for investigation of the their anomalous coulings. However, c c and b b airs will be coiously hoto-roduced at x g of order of 10-5 and 10-4, resectively, and saturation of gluons should manifest itself. Then, there are a number of different hoto-roduction rocesses (including di-jets etc.) which can be investigated at γ colliders. iii) ea otion [1, 18] The main limitation for this otion comes from fast emittance growth due to intrabeam scattering, which is aroximately roortional (Z 2 /A) 2 (γ A ) -3. In this case, the use of flat nucleus beams seems to be more advantageous (as in the case of e otion [10]) because of few times increasing of luminosity lifetime. Nevertheless, sufficiently high luminosity can be achieved at least for light nuclei. For examle, L ec = cm -2 s -1 for collisions of 300 GeV energy electrons beam (Table III) and Carbon beam with n C =

6 and ε C N =1.25π mm mrad (rest of arameters as in Table IV). This value corresonds to L int A 10b -1 er working year (10 7 s) needed from the hysics oint of view [19,20]. Similar to the e otion, the lower limit on β A, which is given by nucleus bunch length, can be overcome by alying a dynamic focusing scheme [9] and an ugrade of the luminosity by a factor 3-4 may be ossible. As mentioned above, the large charge density of nucleus bunch results in strong intrabeam scattering effects and lead to essential reduction of luminosity lifetime ( 1 h for C beam at HERA). There are two ossible solutions of this roblem for TESLA HERA. Firstly, one could consider the ossibility to re-fill nucleus ring at aroriate rate with necessary modifications of the filling time etc. Alternatively, an effective method of cooling of nucleus beam in main ring should be alied, esecially for heavy nuclei. For examle, electron cooling of nucleus beams suggested in [21] for ea otion of HERA can be used for TESLA HERA, also. The basic layout for an ea interaction region can be chosen similar to that for an e otion considered in [7] and [9]. The work on the subject is in rogress [18]. A ossible layout of a detector for TESLA HERA based e collider, which can be used also for ea otion, is resented in [13]. The hysics search rogram of the machine is the direct extension of that for ea otion of HERA (see Chater titled Light and Heavy Nuclei in HERA in [22]). iv) γa otion [1, 18] In my oinion this is a most romising otion of TESLA HERA comlex, because it will give unique oortunity to investigate small x g region in nuclear medium. Indeed, due to the advantage of the real γ sectrum heavy quarks will be roduced via γg fusion at characteristic 2 4 m c( b) xg, 0.9 ( Z / A) s which is aroximately (2 3) 10-5 for charmed hadrons. As in the revious otion, sufficiently high luminosity can be achieved at least for light nuclei. Then, the scheme with deflection of electron beam after conversion is referable because it will give oortunity to avoid limitations from Q A, esecially for heavy nuclei. The deendence of luminosity on the distance between conversion region and interaction oint for TESLA HERA based γc collider is similar to that of the γ otion [16]: L γc = cm -2 s -1 at z=0 and L γc =10 29 cm -2 s -1 at z=10 m with 300 GeV energy electron beam. Let me remind you that an ugrade of the luminosity by a factor 3-4 may be ossible by alying a dynamic focusing scheme. Further increasing of luminosity will require the cooling of nucleus beam in the main ring. Finally, very forward detector in γ-beam direction will be very useful for investigation of small x g region due to registration of charmed and beauty hadrons. Let me finish this section by quoting the aragrah, written taking into mind ea otion of the TESLA HERA comlex but more than alicable for γa otion, from the recent aer [19]: Extension of the x-range by two orders of magnitude at TESLA-HERA collider would corresond to an increase of the gluon densities by a factor of 3 for Q 2 =10 GeV 2. It will definitely bring quark interactions at this scale into the region where DGLAP will e 6

7 break down. For the gluon-induced interactions it would allow the exloration of a non- DGLAP hard dynamics over two orders of magnitude in x in the kinematics where α s is small while the fluctuations of arton densities are large. v) FEL γa otion [23, 24] Colliding of TESLA FEL beam with nucleus bunches from HERA may give a unique ossibility to investigate old nuclear henomena in rather unusual conditions. The main idea is very simle [23]: ultra-relativistic ions will see laser hotons with energy ω 0 as a beam of hotons with energy 2γ A ω 0, where γ A is the Lorentz factor of the ion beam. Moreover, since the accelerated nuclei are fully ionized, we will be free from ossible background induced by low-shell electrons. For HERA γ A =(Z/A)γ =980(Z/A), therefore, the region MeV, which is matter of interest for nuclear sectroscoy, corresonds to kev lasers, which coincide with the energy region of TESLA FEL [4]. The excited nucleus will turn to the ground state at a distance l=γ A τ A c from the collision oint, where τ A is the lifetime of the exited state in the nucleus rest frame and c is the seed of light. For examle, one has l=4mm for 4438 kev excitation of 12 C. Therefore, the detector should be laced close to the collision region. The MeV energy hotons emitted in the rest frame of the nucleus will be seen in the detector as highenergy hotons with energies u to GeV region. The huge number of exected events (~10 10 er day for 4438 kev excitation of 12 C) and small energy sread of colliding beams ( 10-3 for both nucleus and FEL beams) will give oortunity to scan an interesting region with ~1 kev accuracy LEP LHC The interest in this collider, which was widely discussed [25, 26] at earlier stages of LHC roosal, has renewed recently [27]: We consider the LHC e ± otion to be already art of the LHC rogramme The availability of e ± collisions at an energy roughly four times that rovided currently by HERA would allow studies of quark structure down to a size of about cm The discovery of the quark substructure could exlain the Problem of Flavour, or one might discover letoquarks or squarks as resonances in the direct channel i) e otion The recent set of arameters is given in a reort [28] reared at the request of the CERN Scientific Policy Committee. Parameters of roton beam are resented in corresonding column of Table IV. Parameters of electron beam are as follows: E e =67.3 GeV, n e = , ε x /ε y =9.5/2.9nm and β x /β y =85/26cm. With these arameters the estimated luminosity is L e = cm -2 s -1 and exceeds that of the HERA TESLA based e collider. However, the latter has the advantage in kinematics because of comarable values of energies of colliding articles. Moreover, γ collider can not be constructed on the base of LEP LHC (for reasons see [16]). ii) ea otion An estimation of the luminosity for e ± Pb collisions given in [28] seem to be overotimistic because of unaccetable value of Q Pb, which is ~ for roosed set of 7

8 arameters. The one order lower value L e-pb =10 28 cm -2 s -1 is more realistic. However, situation may be different for light nuclei. Again the main advantage of the TESLA HERA comlex in comarison with LEP LHC is γa otion µ ring TEVATRON [29] If the main roblems (high µ roduction rate, fast cooling of µ beam etc.) facing µ + µ roosals are successfully solved, it will also give an oortunity to construct µ colliders. Today only very rough estimations of the arameters of these machines can be made. Two sets of arameters for the collider with two rings, TEVATRON and 200 GeV muon ring, are considered in [29]. Possible arameters of muon beam are resented in Table V and ugraded arameters of TEVATRON roton beam are given in the Table IV (numbers in brackets corresond to otion with low µ roduction rate). Let us mention the large values of roton beam tune in the first otion and roton bunch oulation in the second otion. In my oinion, luminosity values resented in [29] are over-otimistic. For comarison, recent set of 200 GeV muon beam arameters [30], given in the Table V (symbol means transition from 1000 m circumference to TEVATRON), and corresonding arameters from Table IV (roton beam emittance is estimated from Q =0.003) lead to estimation L µ = cm -2 s -1. Nevertheless, with using a larger number of bunches and alying dynamic focusing scheme [9], the value of L µ order of cm -2 s -1 seem to be achievable. Physics search rogram of this machine is similar to that of the e otion of the TESLA HERA comlex. 3. Second stage: Linac LHC and s=3 TeV µ 3.1. Linac LHC The center-of-mass energies which will be achieved at different otions of this machine are an order larger than those at HERA are and ~3 times larger than the energy region of TESLA HERA, LEP LHC and µ ring TEVATRON. In rincile, luminosity values are ~7 times higher than those of corresonding otions of TESLA HERA comlex due to higher energy of rotons. Following [7,8] below we consider electron linac with P e = 60 MW and ugraded roton beam arameters given in the last column of the Table IV. i) e otion [7, 8, 15, 31] According [7, 8] center-of-mass energy and luminosity for this otion are (with obvious modification due to re-scale of E from 8 TeV to 7 TeV): s=5.29 TeV and L e = cm -2 s -1, resectively. Let me remind you that an additional factor 3-4 can be rovided by the dynamic focusing scheme. Further increasing will require cooling at injector stages. This machine, which will extend both the Q 2 -range and x-range by more than two order of magnitude comaring to those exlored by HERA, has a strong otential for both SM and BSM research. 8

9 ii) γ otion [15,16] The advantage in sectrum of back-scattered hotons (for details see ref. [16]) and sufficiently high luminosity (L γ >10 32 cm -2 s -1 ) will clearly manifest itself in a search for different henomena. For examle, thousands di-jets with t >500 GeV and hundreds thousands single W bosons will be roduced, hundred millions of b b- and c c- airs will give oortunity to exlore the region of extremely small x g etc. iii) ea otion [1, 18, 32] In the case of LHC nucleus beam IBS effects in main ring are not crucial because of larger value of γ A. The main rincial limitation for heavy nuclei coming from beambeam tune shift may be weakened using flat beams at collision oint. Rough estimations show that L ea A>10 31 cm -2 s -1 can be achieved at least for light and medium nuclei. iv) γa otion [1, 18, 32] Limitation on luminosity due to beam-beam tune shift is removed in the scheme with deflection of electron beam after conversion. The hysics search otential of this otion, as well as that of revious three otions, needs more investigations from both article and nuclear hysics viewoints. v) FEL γa otion [23, 24] Due to a larger γ A, the requirement on wavelength of the FEL hotons is weaker than in the case of TESLA HERA based FEL γa collider. Therefore, the ossibility of constructing a secial FEL for this otion may be matter of interest. In any case the realization of FEL γa colliders deends on the osition of traditional nuclear hysics community s=4( 3) TeV µ [33] The ossible µ collider with s=4 TeV in the framework of µ + µ roject was discussed in [33] and again over-estimated value of luminosity, namely, L µ = cm -2 s - 1, was considered. Using recent set of arameters [30] for high-energy muon collider with s=3 TeV, one can easily estimate ossible arameters of µ collisions from: N n β µ mµ ε µ Lµ = L +. N µ µ n β m ε µ With n =n µ = we obtain (normalized emittance of the roton beam is estimated from Q =0.003) 0.3cm 105MeV L µ = 7 10 cm s = 10 cm s. 15cm 940MeV 80 In rincile, an ugrade of the luminosity by a factor 3-4 may be ossible by alying a dynamic focusing scheme. This machine is comarable with the e otion of the Linac LHC. 9

10 4. Third stage: e ring VLHC, LSC ELOISATRON and 100 TeV µ 4.1. e ring VLHC Over the last decade two rojects, ELOISATRON [34] and VLHC [35] have been intensively discussed for roton-roton collisions at 100 TeV energy range. The ossible installation of a large electron/ositron ring (to-factory) in VLHC tunnel will give an oortunity to get e collisions with s=7 TeV [36]. Recently, an e collider with s=1 TeV (E e =80 GeV, E =1 TeV) and L e = cm -2 s -1 in a VLHC Booster Tunnel with ~34 km circumference has been roosed [36, 37]. Let me cite the Conclusions from [37]: We have done a reliminary study of an e collider that could be installed in the low field booster of the VLHC. This machine could be oerational before the LEP/LHC and would have a higher luminosity than HERA/TESLA LSC ELOISATRON For obvious reasons I refer to discuss a linac, e. g. Linear Suer Collider [38], as a source of high-energy electron beam. Combination of LSC with ELOISATRON (see Table VI) will give an oortunity to achieve L e = cm -2 s -1 at s=63.2 TeV. Further increasing of luminosity will require alication of dynamic focusing scheme and/or cooling of roton beam. As in the case of TESLA HERA comlex, γ, ea, γa and FEL γa otions essentially extend the caacity of LSC ELOISATRON comlex TeV µ This is a most seculative (however, very attractive) one among the leton-hadron collider otions, which can be foreseen today. Using the luminosity estimation L µµ =10 36 cm -2 s -1 for s=100 TeV µ + µ collider [39] one can exect at n =n µ 0.25cm 105MeV L µ L µµ 10 cm s. 10cm 940MeV Conclusion It seems that neither HERA nor LHC LEP will be the end oints for leton-hadron colliders. Linac-ring tye e machines and ossibly µ colliders will give an oortunity to go far in this direction (see Table VII). However, more activity is needed both in accelerator (further exloration of dynamic focusing scheme, a search for effective cooling methods etc.) and hysics search rogram asects. Acknowledgements I would like to exress my gratitude to DESY Directorate for invitation and hositality. I am grateful to D. Barber, V. Borodulin, R. Brinkmann, O. Cakir, A. Celikel, A. K. Ciftci, L. Frankfurt, P. Handel, M. Klein, M. Leenen, C. Niebuhr, M. Strikman, V. Telnov, D. Trines, G. A. Voss, A. Wagner, F. Willeke and O. Yavas for useful and stimulating discussions. Secial thanks are to N. Walker for careful reading of the manuscrit and valuable comments. My work on the subject was strongly encouraged by 10

11 the suort of Professor B. Wiik, who ersonally visited Ankara in 1996 and signed the Collaboration Agreement between DESY and Ankara University. This work is suorted in art by Turkish State Planning Organization under the grant number 97K References R. Brinkmann et al., Linac-Ring Tye Colliders: Fourth Way to TeV Scale, DESY (1997). 2. S. Atag et al. (Eds.), Proceedings of the First International Worksho on Linac-Ring Tye e and γ Colliders (9-11 Aril 1997, Ankara, Turkey), ublished in Turkish J. Phys. 22 (1998) S. Sultansoy, Four Ways to TeV Scale, Turkish J. Phys. 22 (1998) R. Brinkmann et al. (Eds.), Concetual design of a 500 GeV e + e linear collider with integrated X-ray laser facility, DESY , ECFA D. Trines, A review of e + e Linear Colliders, Turkish J. Phys. 22 (1998) A. Wagner, The Future of HERA and DESY, Talk given at 7 th International Worksho on Dee Inelastic Scattering and QCD (19-23 Aril 1999, Zeuthen, Germany). 7. M. Tigner, B. Wiik and F. Willeke, An Electron-Proton Collider in the TeV Range, Proceedings of the 1991 IEEE Particle Accelerators Conference (6-9 May 1991, San Francisco, California), vol. 5, B. H. Wiik, Recent Develoments in Accelerators, Proceedings of the International Eurohysics Conference on High Energy Physics (22-28 July 1993, Marseille, France), R. Brinkmann and M. Dohlus, A method to overcome the bunch length limitations on β for electron-roton colliders, DESY-M (1995). 10. R. Brinkmann, Interaction Region and Luminosity Limitations for the TESLA/HERA e/ Collider, Turkish J. Phys. 22 (1998) htt:// 12. C. Caso et al., Review of Particle Physics, The Euroean Journal of Physics C3 (1998) A. De Roeck, Toics of Physics Potential and Detector Asects of the LC-HERA e Collider, Turkish J. Phys. 22 (1998) S.I. Alekhin et al., Physics at γ Colliders of TeV Energies, Int. J. Mod. Phys. A6 (1991) S.F. Sultanov, Prosects of the future e and γ colliders: luminosity and hysics, IC/89/409, Trieste (1989). The main contents of this rerint was ublished later in: Z.Z. Aydin, V.M. Maniyev and S.F. Sultansoy, High energy γ colliders: a new facility for elementary article hysics, Part. World 4 (1994) 22; Z.Z. Aydin, A.K. Ciftci and S. Sultansoy, Linac-ring tye e machines and γ colliders based on them, Nucl. Instrum. Meth. A351 (1994) A.K. Ciftci, S. Sultansoy, S. Turkoz and O. Yavas, Main arameters of TeV energy γ colliders, Nucl. Instrum. Meth. A365 (1995) V.I. Telnov, Problems in obtaining γγ and γe colliding beams at linear colliders, Nucl. Instrum. Meth. A294 (1990) S. Sultansoy et al., Main Parameters of Linac-Ring Tye e-nucleus and γ-nucleus Colliders, in rearation. 11

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13 Table I. Parameters of electron beams for s=500 GeV linear colliders TESLA JLC (C) JLC/NLC CLIC Linac reetition rate (Hz) No. of articles/bunch (10 10 ) No. of bunches/ulse Bunch searation (ns) Beam ower (MW) γε x /γε y (mm mrad) 10/ / / /0.1 β x /β y (mm) 15/0.4 15/0.2 12/ /0.1 σ x /σ y at IP (nm) 535/5 318/ / /4.5 σ z (µm) Table II. Parameters of roton beams HERA TEVATRON LHC Beam energy (TeV) No. of articles/bunch (10 10 ) No. of bunches/ring Bunch searation (ns) ε ( 10-9 π rad m) β x /β y (m) 7/ / /0.5 σ x /σ y at IP (µm) 265/50 34/34 16/16 σ z (cm) Table III. Ugraded arameters of the TESLA electron beams Electron energy, GeV Number of electrons er bunch, Number of bunches er ulse Beam ower, MW Bunch length, mm Bunch sacing, ns Reetition rate, Hz

14 Table IV. Ugraded arameters of roton beams TESLA HERA LEP LHC µ TEVATRON Linac LHC No of rotons er (500) bunch, No of bunches er ~800 ring Bunch sacing, ns ε N, 10-6 m (50) σ z, cm β, cm 20 16/1.5 m σ x,y at IP, µm /28 40 (90) Q, / (5) Table V. Parameters of muon beams µ high (low) Recent set Resent set Energy, GeV Number of muons er bunch, (50) Number of bunches er ring Number of turns er ulse Pulse rate, Hz 30 (10) ε N µ, 10-6 m 50 (200) β µ, cm

15 Table VI. Parameters of the future multi-tev beams Particles (ELOISATRON) e ± (LSC) µ ± ( s=100 TeV µ + µ ) Energy, TeV Number of articles er bunch, Number of bunches er ulse Number of bunches er ring Bunch searation, m Reetition rate, Hz Number of turns ε N, 10-6 m σ x,y, 10-6 m β, cm Table VII. Future leton-hadron colliders: a) First stage ( ) TESLA HERA LEP LHC µ-ring Tevatron s, TeV 1.05 (1.35) E l, TeV 0.3 (0.5) E, TeV L, cm -2 s Main limitations P e, ε, β Q e, Q n µ, ε µ, Q, ε, β Additional otions ea, γ, γa, FEL γa ea µa (?) b) Second ( ) and third (>2020) stages Linac LHC µ LSC ELOISATRON µ s, TeV E l, TeV E, TeV L, cm -2 s Otions ea, γ, γa, FEL γa µa (?) ea, γ, γa, FEL γa µa (?) 15