DESY 99-159 ISSN 0418-9833
AU-HEP-99/02 
October 1999





The post-HERA era: brief review of future lepton-hadron and
photon-hadron colliders





S. Sultansoy


Deutsches Elektronen-Synchrotron DESY, Hamburg, Germany
Department of Physics, Faculty of Sciences, Ankara University, Turkey
Institute of Physics, Academy of Sciences, Baku, Azerbaijan





Abstract


Options for future lp, lA, p, A and FEL A colliders are discussed.

 v2 25 Nov 1999





1


CONTENTS


1. INTRODUCTION


2. FIRST STAGE: TESLA


HERA, LEP


LHC and ----ring


TEVATRON
2.1. TESLA


HERA complex
i) ep option
ii) p option
iii) eA option
iv) A option
v) FEL A option
2.2. LEP


LHC
i) ep option
ii) eA option
2.3. 
----ring


TEVATRON

3. SECOND STAGE: Linac


LHC and s====3 TeV p
3.1. Linac


LHC
i) ep option
ii) p option
iii) eA option
iv) A option
v) FEL A option
3.2.
s====3333 TeV p

4. THIRD STAGE: e-
---ring


VLHC, LSC


ELOISATRON and multi-TeV p
4.1. e-
---ring


VLHC
4.2. LSC


ELOISATRON
4.3. Multi-TeV 
p

5. CONCLUSION





2


1. Introduction
It is known that lepton-hadron collisions have been playing a crucial role in
exploration of deep inside of Matter. For example, the quark-parton model was originated
from investigation of electron-nucleon scattering. HERA has opened a new era in this
field extending the kinematics region by two orders both in high Q2 and small x
compared to fixed target experiments. However, the region of sufficiently small x and
simultaneously high Q2 (10 GeV2), where saturation of parton densities should manifest
itself, is currently not achievable. It seems possible that eA option of HERA will give
opportunity to observe such phenomena. Then, the acceleration of polarized protons in
HERA could provide clear information on nucleon spin origin.
The investigation of physics phenomena at extreme small x but sufficiently high Q2 is
very important for understanding the nature of strong interactions at all levels from
nucleus to partons. At the same time, the results from lepton-hadron colliders are
necessary for adequate interpretation of physics at future hadron colliders. Today, linac-
ring type ep machines seem to be the main way to TeV scale in lepton-hadron collisions;
however, it is possible that in future p machines can be added depending on solutions of
principal issues of basic +- 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 ----ring


TEVATRON

2.1. TESLA


HERA complex
Construction of future lepton linacs tangentially to hadron rings (HERA, Tevatron or
LHC) will provide a number of additional opportunities to investigate lepton-hadron and
photon-hadron interactions at TeV scale (see [1-3] and references therein). For example:


TESLAHERA = TESLA HERA
TeV scale ep collider
TeV scale p collider
eA collider
A collider
FEL A collider.

The future options to collide electron and photon beams from TESLA with proton
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 p and A options are unique
features of linac-ring type machines and can not be realized at LEPLHC, which is
comparable with TESLAHERA ep and eA options.


i) ep option [7-10]
There are a number of reasons favoring a superconducting linear collider (TESLA) as
a source of e-beam for linac-ring colliders. First of all spacing between bunches in warm
linacs, which is of the order of ns (see Table I) [11], doesn't match with the bunch
spacing in the HERA, TEVATRON and LHC (see Table II) [12]. Also the pulse length is



3


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 transparent expression for the luminosity of this collider is [8]:
1 P n
L = e
ep p p
N

4 E
e p p

for round, transversely matched beams. Using the values of upgraded parameters of
TESLA electron beam from Table III and HERA proton beam from Table IV, we obtain
Lep=1.31031cm-2s-1 for Ee=300 GeV option.

The lower limit on p , which is given by proton bunch length, can be overcome by
applying a "dynamic" focusing scheme [9], where the proton bunch waist travels with

electron bunch during collision. In this scheme p is limited, in principle, by the electron
bunch length, which is two orders magnitude smaller. More conservatively, an upgrade of
the luminosity by a factor 3-4 may be possible. Therefore, luminosity values exceeding
1031cm-2s-1 seems to be achievable for all three options given in Table III.
Further increasing of luminosity can be achieved by increasing the number of protons
in bunch and/or decreasing of normalized emittance. This requires the application of
effective cooling methods at injector stages. Moreover, cooling in the HERA ring may be
necessary in order to compensate emittance growth due to intra-beam scattering [10].
First studies of the beam optics in the interaction region are presented in [7] and [9],
where head-on collisions are assumed. The basic concept consists of common focusing
elements for both the electron and the proton beams and separating the beams outside of
the low-beta insertion. However, collisions with small crossing angle (100 rad) are
also a matter of interest, especially for p and A options (see below). Further work on the
subject, including the detector aspects, is very important.
In principle, TESLAHERA based ep collider will extend the HERA kinematics
region by an order in both Q2 and x and, therefore, the parton saturation regime can be
achieved. A brief account of some SM physics topics (structure functions, hadronic final
states, high Q2 region etc.) is presented in [13], where a possible upgrade of the H1
detector is considered. The BSM search capacity of the machine will be defined by future
results from LHC. If the first family leptoquarks and/or leptogluons have masses less than
1 TeV they will be produced copiously (for couplings of order of em). The indirect
manifestation of new gauge bosons may also be a matter of interest. In general, the
physics search program of the machine is a direct extension of the HERA search
program.


ii) p option [14-16]
Earlier, the idea of using high energy photon beams obtained by Compton
backscattering of laser light off a beam of high energy electrons was considered for e
and colliders (see [17] and references therein). Then the same method was proposed in
[14] for constructing p colliders on the base of linac-ring type ep machines. Rough
estimations of the main parameters of p collisions are given in [15]. The dependence of
these parameters on the distance z between conversion region and collision point was
analyzed in [16], where some design problems were considered.



4


Referring for details to [16] let me note that Lp=2.61031cm-2s-1 at z=10 cm for
TESLAHERA based p collider with 300 GeV energy electrons beam. Then, the
luminosity slowly decreases with the increasing z (factor ~1/2 at z=10 m) and opposite
helicity values for laser and electron beams are advantageous. Additionally, a better
monochromatization of high-energy photons seen by proton bunch can be achieved by
increasing the distance z. Finally, let me remind you that an upgrade of the luminosity by
a factor 3-4 may be possible by applying a "dynamic" focusing scheme.
The scheme with non-zero crossing angle and electron beam deflection considered in
[16] for p option lead to problems due to intensive synchrotron radiation of bending
electrons and necessity to avoid the passing of electron beam from the proton beam
focusing quadrupoles. 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 proton beam together with high-energy beam, but because of larger cross-
section of p interaction the background resulting from ep collisions may be neglected.
The problem of over-focussing of the electron beam by the strong proton-low-
quadrupoles 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 Compton 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) m at the distance of 25 m
from conversion region and the focusing quadrupoles for proton beam have negligible
influence on the residual electrons. On the other hand, in the scheme with deflection there
is no restriction on ne from Qp, therefore, larger ne and bunch spacing may be
preferable. All these topics need a further research.
Concerning the experimental aspects, very forward detector in -beam direction will
be very useful for investigation of small xg region due to registration of charmed and

beauty hadrons produced via gQ Q sub-process.
There are a number of papers (see [3] and refs. therein), devoted to physics at p
colliders. Concerning the BSM physics, p option of TESLAHERA doesn't promise
essential results with possible exclusions of the first family excited quarks (if their
masses are less than 1 TeV) and associate production of gaugino and first family squarks
(if the sum of their masses are less than 0.5 TeV). The photo-production of W and Z
bosons may be also the matter of interest for investigation of the their anomalous

couplings. However, c c and b b pairs will be copiously photo-produced at xg of order of
10-5 and 10-4, respectively, and saturation of gluons should manifest itself. Then, there are
a number of different photo-production processes (including di-jets etc.) which can be
investigated at p colliders.

iii) eA option [1, 18]
The main limitation for this option comes from fast emittance growth due to intra-
beam scattering, which is approximately proportional (Z2/A)2(A)-3. In this case, the use of
flat nucleus beams seems to be more advantageous (as in the case of ep option [10])
because of few times increasing of luminosity lifetime. Nevertheless, sufficiently high
luminosity can be achieved at least for light nuclei. For example, LeC=1.11029cm-2s-1 for
collisions of 300 GeV energy electrons beam (Table III) and Carbon beam with nC=8109



5


and N
C =1.25mmmrad (rest of parameters as in Table IV). This value corresponds to
LintA10pb-1 per working year (107 s) needed from the physics point of view [19,20].

Similar to the ep option, the lower limit on A , which is given by nucleus bunch length,
can be overcome by applying a "dynamic" focusing scheme [9] and an upgrade of the
luminosity by a factor 3-4 may be possible.
As mentioned above, the large charge density of nucleus bunch results in strong intra-
beam scattering effects and lead to essential reduction of luminosity lifetime ( 1 h for C
beam at HERA). There are two possible solutions of this problem for TESLAHERA.
Firstly, one could consider the possibility to re-fill nucleus ring at appropriate rate with
necessary modifications of the filling time etc. Alternatively, an effective method of
cooling of nucleus beam in main ring should be applied, especially for heavy nuclei. For
example, electron cooling of nucleus beams suggested in [21] for eA option of HERA can
be used for TESLAHERA, also.
The basic layout for an eA interaction region can be chosen similar to that for an ep
option considered in [7] and [9]. The work on the subject is in progress [18]. A possible
layout of a detector for TESLAHERA based ep collider, which can be used also for eA
option, is presented in [13].
The physics search program of the machine is the direct extension of that for eA
option of HERA (see Chapter titled "Light and Heavy Nuclei in HERA" in [22]).


iv) A option [1, 18]
In my opinion this is a most promising option of TESLAHERA complex, because it
will give unique opportunity to investigate small xg region in nuclear medium. Indeed,
due to the advantage of the real spectrum heavy quarks will be produced via g fusion
at characteristic

4m2c(b)
x ,
g 9
.
0  (Z / A)  sep
which is approximately (23)10-5 for charmed hadrons.
As in the previous option, sufficiently high luminosity can be achieved at least for
light nuclei. Then, the scheme with deflection of electron beam after conversion is
preferable because it will give opportunity to avoid limitations from QA, especially for
heavy nuclei. The dependence of luminosity on the distance between conversion region
and interaction point for TESLAHERA based C collider is similar to that of the p
option [16]: LC=21029cm-2s-1 at z=0 and LC=1029cm-2s-1 at z=10 m with 300 GeV energy
electron beam. Let me remind you that an upgrade of the luminosity by a factor 3-4 may
be possible by applying a "dynamic" focusing scheme. Further increasing of luminosity
will require the cooling of nucleus beam in the main ring. Finally, very forward detector
in -beam direction will be very useful for investigation of small xg region due to
registration of charmed and beauty hadrons.
Let me finish this section by quoting the paragraph, written taking into mind eA
option of the TESLAHERA complex but more than applicable for A option, from the
recent paper [19]:
"Extension of the x-range by two orders of magnitude at TESLA-HERA collider
would correspond to an increase of the gluon densities by a factor of 3 for Q2=10 GeV2. It
will definitely bring quark interactions at this scale into the region where DGLAP will



6


break down. For the gluon-induced interactions it would allow the exploration of a non-
DGLAP hard dynamics over two orders of magnitude in x in the kinematics where s is
small while the fluctuations of parton densities are large."


v) FEL A option [23, 24]
Colliding of TESLA FEL beam with nucleus bunches from HERA may give a unique
possibility to investigate "old" nuclear phenomena in rather unusual conditions. The main
idea is very simple [23]: ultra-relativistic ions will see laser photons with energy 0 as a
beam of photons with energy 2
A 0, where A is the Lorentz factor of the ion beam.
Moreover, since the accelerated nuclei are fully ionized, we will be free from possible
background induced by low-shell electrons. For HERA A=(Z/A)p=980(Z/A), therefore,
the region 0.110 MeV, which is matter of interest for nuclear spectroscopy, corresponds
to 0.110 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=
A A c from the
collision point, where A is the lifetime of the exited state in the nucleus rest frame and c
is the speed of light. For example, one has l=4mm for 4438 keV excitation of 12C.
Therefore, the detector should be placed close to the collision region. The MeV energy
photons emitted in the rest frame of the nucleus will be seen in the detector as high-
energy photons with energies up to GeV region.
The huge number of expected events (~1010 per day for 4438 keV excitation of 12C)
and small energy spread of colliding beams (10-3 for both nucleus and FEL beams) will
give opportunity to scan an interesting region with ~1 keV accuracy.


2.2. LEP


LHC
The interest in this collider, which was widely discussed [25, 26] at earlier stages of
LHC proposal, has renewed recently [27]:

"We consider the LHC e p option to be already part of the LHC programme... The

availability of e p collisions at an energy roughly four times that provided currently by
HERA would allow studies of quark structure down to a size of about 10-17 cm... The
discovery of the quark substructure could explain the Problem of Flavour, or one might
discover leptoquarks or squarks as resonances in the direct channel..."


i) ep option
The recent set of parameters is given in a report [28] prepared at the request of the
CERN Scientific Policy Committee. Parameters of proton beam are presented in
corresponding column of Table IV. Parameters of electron beam are as follows: Ee=67.3

GeV, ne=6.41010, x/y=9.5/2.9nm and x /y =85/26cm. With these parameters the
estimated luminosity is Lep=1.21032cm-2s-1 and exceeds that of the HERATESLA based
ep collider. However, the latter has the advantage in kinematics because of comparable
values of energies of colliding particles. Moreover, p collider can not be constructed on
the base of LEPLHC (for reasons see [16]).

ii) eA option

An estimation of the luminosity for e Pb collisions given in [28] seem to be over-
optimistic because of unacceptable value of QPb, which is ~7010-3 for proposed set of



7


parameters. The one order lower value Le-Pb=1028cm-2s-1 is more realistic. However,
situation may be different for light nuclei. Again the main advantage of the
TESLAHERA complex in comparison with LEPLHC is A option.

2.3. 
----ring


TEVATRON [29]
If the main problems (high -production rate, fast cooling of -beam etc.) facing
+- proposals are successfully solved, it will also give an opportunity to construct p
colliders. Today only very rough estimations of the parameters of these machines can be
made. Two sets of parameters for the collider with two rings, TEVATRON and 200 GeV
muon ring, are considered in [29]. Possible parameters of muon beam are presented in
Table V and upgraded parameters of TEVATRON proton beam are given in the Table IV
(numbers in brackets correspond to option with low -production rate). Let us mention
the large values of proton beam tune in the first option and proton bunch population in
the second option. In my opinion, luminosity values presented in [29] are over-optimistic.
For comparison, recent set of 200 GeV muon beam parameters [30], given in the Table V
(symbol means transition from 1000 m circumference to TEVATRON), and
corresponding parameters from Table IV (proton beam emittance is estimated from
Qp=0.003) lead to estimation Lp=1.71031cm-2s-1. Nevertheless, with using a larger
number of bunches and applying "dynamic" focusing scheme [9], the value of Lp order
of 1032cm-2s-1 seem to be achievable.
Physics search program of this machine is similar to that of the ep option of the
TESLAHERA complex.


3. Second stage: Linac


LHC and s=3 TeV p

3.1. Linac


LHC
The center-of-mass energies which will be achieved at different options of this
machine are an order larger than those at HERA are and ~3 times larger than the energy
region of TESLAHERA, LEPLHC and -ringTEVATRON. In principle,
luminosity values are ~7 times higher than those of corresponding options of
TESLAHERA complex due to higher energy of protons. Following [7,8] below we
consider electron linac with Pe= 60 MW and upgraded proton beam parameters given in
the last column of the Table IV.


i) ep option [7, 8, 15, 31]
According [7, 8] center-of-mass energy and luminosity for this option are (with
obvious modification due to re-scale of Ep from 8 TeV to 7 TeV): s=5.29 TeV and
Lep=81031cm-2s-1, respectively. Let me remind you that an additional factor 3-4 can be
provided by the "dynamic" focusing scheme. Further increasing will require cooling at
injector stages.
This machine, which will extend both the Q2-range and x-range by more than two
order of magnitude comparing to those explored by HERA, has a strong potential for
both SM and BSM research.





8


ii) p option [15,16]
The advantage in spectrum of back-scattered photons (for details see ref. [16]) and
sufficiently high luminosity (L >
p 1032cm-2s-1) will clearly manifest itself in a search for
different phenomena. For example, thousands di-jets with p >
t 500 GeV and hundreds

thousands single W bosons will be produced, hundred millions of b b- and c c- pairs will
give opportunity to explore the region of extremely small xg etc.


iii) eA option [1, 18, 32]
In the case of LHC nucleus beam IBS effects in main ring are not crucial because of
larger value of A. The main principal limitation for heavy nuclei coming from beam-
beam tune shift may be weakened using flat beams at collision point. Rough estimations
show that L
eA A>1031cm-2s-1 can be achieved at least for light and medium nuclei.


iv) A option [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 physics search potential of this option, as well as that of previous three options,
needs more investigations from both particle and nuclear physics viewpoints.


v) FEL A option [23, 24]
Due to a larger A, the requirement on wavelength of the FEL photons is weaker than
in the case of TESLAHERA based FEL A collider. Therefore, the possibility of
constructing a special FEL for this option may be matter of interest. In any case the
realization of FEL A colliders depends on the position of "traditional" nuclear physics
community.


3.2.
s====4(


3) TeV p [33]
The possible p collider with s=4 TeV in the framework of +- project was
discussed in [33] and again over-estimated value of luminosity, namely, Lp=31035cm-2s-
1, was considered. Using recent set of parameters [30] for high-energy muon collider with
s=3 TeV, one can easily estimate possible parameters of p collisions from:

n p m N
L .
p =    L + -
N  
n m
p p p
With np=n=21012 we obtain (normalized emittance of the proton beam is estimated from
Qp=0.003)
.
0 3cm 105MeV 50 34 -2 1
- 32 -2 1
L .
p
 = 7 10 cm s = 10 -
cm s
15cm 940MeV 80
In principle, an upgrade of the luminosity by a factor 3-4 may be possible by applying a
"dynamic" focusing scheme.
This machine is comparable with the ep option of the LinacLHC.





9


4. Third stage: e-
---ring


VLHC, LSC


ELOISATRON and 100 TeV p

4.1. e-
---ring


VLHC
Over the last decade two projects, ELOISATRON [34] and VLHC [35] have been
intensively discussed for proton-proton collisions at 100 TeV energy range. The possible
installation of a large electron/positron ring (top-factory) in VLHC tunnel will give an
opportunity to get ep collisions with s=7 TeV [36]. Recently, an ep collider with s=1
TeV (Ee=80 GeV, Ep=1 TeV) and Lep=3.21032cm-2s-1 in a VLHC Booster Tunnel with
~34 km circumference has been proposed [36, 37]. Let me cite the Conclusions from
[37]:
"We have done a preliminary study of an ep collider that could be installed in the low
field booster of the VLHC. This machine could be operational before the LEP/LHC and
would have a higher luminosity than HERA/TESLA."


4.2. LSC


ELOISATRON
For obvious reasons I prefer to discuss a linac, e. g. Linear Super Collider [38], as a
source of high-energy electron beam. Combination of LSC with ELOISATRON (see
Table VI) will give an opportunity to achieve Lep=31032cm-2s-1 at s=63.2 TeV. Further
increasing of luminosity will require application of "dynamic" focusing scheme and/or
cooling of proton beam.
As in the case of TESLAHERA complex, p, eA, A and FEL A options essentially
extend the capacity of LSCELOISATRON complex.

4.3. 100 TeV 
p
This is a most speculative (however, very attractive) one among the lepton-hadron
collider options, which can be foreseen today. Using the luminosity estimation
L=1036cm-2s-1 for s=100 TeV +- collider [39] one can expect at np=n
2
.
0 5cm 105MeV .
8 7 33 -2 1
-
L p
 L 10 cm s .
10cm 940MeV 30


5. Conclusion
It seems that neither HERA nor LHCLEP will be the end points for lepton-hadron
colliders. Linac-ring type ep machines and possibly p colliders will give an opportunity
to go far in this direction (see Table VII). However, more activity is needed both in
accelerator (further exploration of "dynamic" focusing scheme, a search for effective
cooling methods etc.) and physics search program aspects.



Acknowledgements
I would like to express my gratitude to DESY Directorate for invitation and
hospitality. 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. Special thanks are to N. Walker for careful reading of the
manuscript and valuable comments. My work on the subject was strongly encouraged by



10


the support of Professor B. Wiik, who personally visited Ankara in 1996 and signed the
Collaboration Agreement between DESY and Ankara University.
This work is supported in part by Turkish State Planning Organization under the grant
number 97K-120-420.


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Table I. Parameters of electron beams for s=500 GeV linear colliders

TESLA JLC (C) JLC/NLC CLIC
Linac repetition rate (Hz) 5 100 120 200
No. of particles/bunch (1010) 2 1.11 0.95 0.4
No. of bunches/pulse 2820 72 95 150
Bunch separation (ns) 337 2.8 2.8 0.67
Beam power (MW) 11.3 3.07 4.5 4.81
x/y (mmmrad) 10/0.03 3.3/0.05 4.5/0.1 1.88/0.1

x /y (mm) 15/0.4 15/0.2 12/0.12 10/0.1
x/y at IP (nm) 535/5 318/4.3 330/4.9 196/4.5
z (m) 400 200 120 50




Table II. Parameters of proton beams


HERA TEVATRON LHC
Beam energy (TeV) 0.92 1 7
No. of particles/bunch (1010) 7 27 10.5
No. of bunches/ring 180 36 2835
Bunch separation (ns) 96 396 25
( 10-9 radm) 5 3.5 0.5

x /y (m) 7/0.5 0.35/0.35 0.5/0.5
x/y at IP (m) 265/50 34/34 16/16
z (cm) 8.5 38 7.5




Table III. Upgraded parameters of the TESLA electron beams


Electron energy, GeV 300 500 800
Number of electrons per bunch, 1010 1.8 21.5 1.41
Number of bunches per pulse 4640 28204950 45004430
Beam power, MW 40 22.630 24.440
Bunch length, mm 1 0.4 0.3
Bunch spacing, ns 192 337192 189192
Repetition rate, Hz 10 5 35





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Table IV. Upgraded parameters of proton beams

TESLAHERA LEPLHC p TEVATRON LinacLHC
No of protons per 30 10 125 (500) 200 30
bunch, 1010
No of bunches per 90 508 24 ~800
ring
Bunch spacing, ns 192 100 7128 100
N
p , 10-6 m 0.8 3.75 12.5 (50) 80 0.8
z, cm 15 7.5 15 7.5
p, cm 20 16/1.5 m 15 10
x,y at IP, m 12.5 90/28 40 (90) 106 3.3
Qp, 10-4 27 32/10 200 (5) 30 20





Table V. Parameters of muon beams

p high (low) Recent set Resent set
Energy, GeV 200 200 1500
Number of muons per bunch, 1010 200 (50) 200 200
Number of bunches per ring 2 4 4
Number of turns per pulse 2000 700100 785
Pulse rate, Hz 30 (10) 15 15
N
 , 10-6 m 50 (200) 50 50

 , cm 7.5 2.6 0.3





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Table VI. Parameters of the future multi-TeV beams

Particles p (ELOISATRON) 
e (LSC)  ( s=100 TeV +-)
Energy, TeV 100 10 50
Number of particles 0.5130 0.041 80
per bunch, 1010
Number of bunches - 1 1
per pulse
Number of  - 1
per ring
Bunch separation, m 510000 10000 100000
Repetition rate, Hz - 30000 7.9
Number of turns - - 1350
N, 10-6 m 0.9 0.04 8.7
x,y, 10-6m 0.670.3 0.002 0.21
, cm 5010 0.1 0.25




Table VII. Future lepton-hadron colliders:


a) First stage (2010-2015)
TESLAHERA LEPLHC -ringTevatron
s, TeV 1.05 (1.35) 1.79 1.37 0.89
El, TeV 0.3 (0.5) 0.8 0.0673 0.2
Ep, TeV 0.92 1 7 1
L, 1031cm-2s-1 110 12 110
Main limitations
P
e, p, p Qe, Qp n, , Qp, p, p
Additional options eA, p, A, FEL A eA A (?)

b) Second (2015-2020) and third (>2020) stages
LinacLHC p LSCELOISATRON p
s, TeV 5.29 3 63.2 100
El, TeV 1 1.5 10 50
Ep, TeV 7 1.5 100 50
L, 1031cm-2s-1 10100 10100 1001000 1001000
Options eA, p, A, FEL A A (?) eA, p, A, FEL A A (?)





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