The 14th Symposium on Accelerator Science and Technology, Tsukuba, Japan, November 2003

STATUS OF THE PF RING AND ITS NEW UPGRADE PROJECT
M. Kobayashi, S. Asaoka, K. Haga, K. Harada, T. Honda, Y. Hori, M. Izawa, T. Kasuga,
Y. Kobayashi, H. Maezawa, Y. Minagawa, A. Mishina, T. Mitsuhashi, T. Miyajima, H. Miyauchi,S. Nagahashi, T. Nogami, T. Obina, C.O. Pak, S. Sakanaka, Y. Sato, T. Shioya, M. Tadano,T. Takahashi, Y. Tanimoto, K. Tsuchiya, T. Uchiyama, A. Ueda, K. Umemori, S. Yamamoto,Photon Factory, KEK, Tsukuba, Japan
While six insertion devices including one superconducting wiggler are currently in operation, we haveproceeded with a new upgrade project to create six new
short-straight sections and to lengthen the existing straightsections. The short-straight sections will provide an
opportunity to install short-period narrow-gap undulators,
and the extension of existing straight sections will betaken advantage of updating current insertion devices tothe latest models in future. As a part of the project, twostraight sections of B04-B05 and B18-B19 have beenreconstructed to extend their free space and a new
multipole wiggler has been installed at BL-5 in thesummer shutdown of 2003. The whole reconstruction for
the upgrade project will be completed in FY 2005.

effective user time excluding time lost due to machine
trouble and daily injections was 4179 hours. Its ratio tothe scheduled time was 98 %. Total failure time during
the FY 2002 was 20.8 hours, and the failure rate, definedas the failure time to the total operation time, was about
0.4 %. This failure rate was the lowest during the 21-year
operation since 1982.
6000
5000

Operation Time (hrs)

Abstract

Operation Time
Scheduled Time
Effective User Time

4000
3000
2000
1000
0

INTRODUCTION
Since the first commissioning in 1982 as one of thepioneering second-generation synchrotron light sources,the 2.5-GeV Photon Factory (PF) storage ring has been
upgraded twice in 1986 and 1997 [1] in order to reducethe beam emittance from 450 nmrad to 36 nmrad. In 1997,
the ring lattice was largely reconstructed by thereinforcement of the quadrupole magnets and thesextupole magnets in the normal cell sections. At thesame time, some hardwares such as the RF cavities [2]and the orbit stabilization system [3] were renewed. As aresult, the stability and reliability of the machine
operation have been improved greatly.
The PF ring has had seven free straight sections for
insertion devices since the beginning. During the summer
shutdown of 2003, a new multipole wiggler [4] has been
installed into BL-5, and a new beamline for protein
crystallography is in commissioning now. The BL-5 was
the last free straight section in the present configuration.
Increasing needs for the undulator radiation in the x-ray
range, including higher harmonics, and demands forvarious types of new insertion devices prompted us tocontemplate the new upgrade program. The main purposeof the present project is not an emittance reduction, but toproduce new short-straight sections and to extend existingstraight sections.

OPERATION STATUS
A history of the operation time from the firstcommissioning is shown in figure 1. In FY 2002, the total
operation time was 5130 hours. It slightly decreased fromthe previous year due to the renewal of the PF computer
system. Scheduled user time was 4267 hours, and the1985

1990

1995

2000

Fiscal Year

Figure 1: Operation time history of the PF ring.
The PF ring is usually operated in a multiple bunchmode with an initial current of 450 mA. The higher
energy operation is also available at 3 GeV with a lower
initial current of 200 mA. Two periods of 3-GeV
operation was scheduled during the FY 2002, and its total
time was about 3 weeks. The product of beam current I
and the beam lifetime t (It) was about 1300 A min in2002. Even though the beam emittance has been much
lower, the lifetime recovers a comparable value as before
the low-emittance reconstruction [5].
Manufacturing of traveling wave kicker magnet wascompleted, and the new kicker magnet system started theoperation in October 2002. By a shorter pulse length anda larger kick angle of the new system, a wide acceptancefor the injected beam has been obtained. The efficiency
and stability of the injection have been improved [6].
Study to search for practical operation near thetheoretically minimum emittance of the present lattice has
been performed successfully in reducing the emittance to28 nmrad, and a practical injection rate was obtained byusing the new kicker system even under the lower
emittance operation [7].

NEW UPGRADE PROJECT
Outline of the upgrade project
An overview of the project is given in figure 2. The
main part of this project is modification of the latticeconfiguration around the straight sections, keeping theorbital polygon itself. As done in the second upgrade

The 14th Symposium on Accelerator Science and Technology, Tsukuba, Japan, November 2003

program in 1997 for the normal-cell sections, we will
replace existing quadrupole magnets with new ones
having shorter length and higher field gradient, and placethem closer to the adjoining bending magnets. Due to thismodification, new straight sections of 1.4 m (in freespace) will be produced, and the existing straight sections
will be almost doubled in their free space. Such
BL-1
'02 Summer

BL-2'03 Spring
BL-3
B03'03 Spring

MPW#5'03 Summer

BL-28'03 Summer

3.7m -> 5.1m

BL-27

Undulator#2
MPW#28B280m -> 1.4m
4.3m -> 5.7m B27

Upgrade of
Septum Magnet

3.7m -> 5.1m

Replacement of
Vacuum Chambers

B05

Replacement of Q magnet
Replacement of Beamline Front-end

B02 5.0m -> 9.0m B010m -> 1.4m
RF
B04 4.3m -> 5.7m

BL-4'03 Spring

modification of lattice configuration, on the other hand,alters the physical boundary conditions around thevacuum chambers in the bending magnets and around thebeamline front ends. To satisfy the new boundary
conditions, preparatory measures such as the installationof redesigned front ends have already been under way
since 2002.

Injection

B26

B06

B25

B07

BL-5
'02 Summer

B24

B08

B23

Normal Cell,
reconstructed in 1997
for Low Emittance

B09

B22
B21

B10
B11

B20

B12

B19

3.7m -> 5.1m

3.7m -> 5.1m

BL-18'03 Summer

MPW#19MPW#13

B13 4.3m -> 5.7m4.3m -> 5.7m B18
VW#140m -> 1.4m0m -> 1.4m
RFBL-17B14
B17
B15 5.0m -> 9.0m B16
MPW#16BL-13'03 Spring

BL-14

BL-15'02 Summer

BL-16

USG#17

Figure 2: Outline of the upgrade project.
5000

750

750

Q152

MPW16Q153

Q154

B16750

VD

750

Q151

VD

B153120(a) Magnet Configration (Present)

400

400
B16VD
Q152
PHV

U16

PHV

8930

Q154

400

PHV
Q153
VD

400
PHV
Q151

7500

B15

The creation of new short-straight sections and theextension of two long-straight sections are illustrated infigures 3 and 4, respectively. The PF storage ring willthen have the straight sections of two 9 m-long, four 5 mlong, four 5.7 m-long, and four 1.4 m-long. When theupgrade alterations are completed, eleven straight sections
among them will be available for insertion devices. In
addition, two short insertion devices may be installed in
the two 5.7 m-long straight sections where the RF cavities
are placed. The dispersion and the beta functions of thosesections are optimized to be as low as possible. Inparticular, the vertical beta function of the short straightsection is reduced to 0.4 m at the minimum value asshown in figure 5, which is very suitable for mini-poleundulators. A beam emittance of 27.5 nmrad is expectedwith the new optics, which is slightly lowered than thepresent value of 36 nmrad.

(b) Magnet Configration (New)PF-Ring New Optics
25
βx
βyVD

β β (m)x, y500

B17180

Q163

1000

Q162

VD500 180

Q161

B162015βy =0.4 m10(a) Magnet Configration (Present)

50(b) Magnet Configration (New)

B1715B17Q171
Q172

Q163
Q164

B16Q161
Q162

Q154

10U17Path Length (m)PHVQ164

VD

300 250 300

PHVQ163

SGU171410

PHVQ162

VD

PHVQ161

B16300 250 300

5Q153

0500

20

The 14th Symposium on Accelerator Science and Technology, Tsukuba, Japan, November 2003

Since the new quadrupole magnets have a different
bore diameter from the old ones, and will be placed very
close to the bending magnets, a number of vacuum
chambers including those in twelve bend sections should
be replaced with new ones. The design of the new B(bending magnet section)-chambers and Q (quadrupole
magnet section)-chambers, including beam-position
monitor (BPM) chambers, has been finished. The
conceptual design of the B-chamber is shown in figure 6.
A prototype chamber is now being manufactured.

B-chamber

SR: 0deg line
SR: 2.5deg line

changeable part

SR portcrotch absorber(SR-slit)

Q-chamber
1160

B-mag
BPM

bellows
BPM

Q-mag
BPM

bellows400

Q-mag BPM
bellows
pumping port/gauge
250

400

215

Q-mag

Q-mag

400
350

1625
orbital radius
R=8663.462

300

25030013751019

λu=1cmλu=1.6cm

Figure 6: Conceptual chamber design in the bend section.
PFE=2.5GeV
I=300mA
ε =27nm

18010The shutdown for installation of new components andrearrangement of related ones is scheduled to take placefrom April to September, 2005. This timetable was
decided on to minimize the loss of user operation time,taking into account the administration of electric power
supply in our country. The removal and installation of theredesigned new components for the front ends werealready started in fiscal 2002 for the beamlines related tothis project and eight front-ends out of twelve have been
replaced by this summer. The new quadrupole magnets
are to be completed in fiscal 2003, and the new vacuum
chambers of the bending-magnet section will be fully
prepared in fiscal 2004. In addition to these main parts ofthis project, the Q-magnet power supplies and the septum
magnet will be replaced; the design of new BPM system
is also in progress with the aim of higher precision beamposition monitoring.
In parallel with these preparatory works, the new Qmagnet arrays were already installed this summer into
downstream end at the two straight sections, B4-5 andB18-19, bordering area between the normal cell andstraight sections. Also in this summer a multipole wiggler
was newly installed into the section B4-5 so as tocomplete a new beamline dedicated to structural biology.

-4

σ /E=7.3×10

REFERENCES

E

βx=5m
βy=0.4m

1015

1014

λu=1.2cm

1016

1013

Time schedule of the project

κ=1%coupling17

λu=2cmBrilliance (phs/s/mm2/mrad2/0.1%bw)

10these short-period undulators, sufficiently high brilliancewithin a spectral range from 8 to 16 keV will be available.
This spectral range is desired by the majority of x-ray
research fields, especially the field of structural biology.

min gap=4.5mm
L=0.5m05,00010,00015,00020,00025,00030,000

Energy (eV)Figure 7: Example spectra of the radiation from shortperiod narrow-gap undulators.

Expected spectra of short period undulators
Figure 7 shows the expected radiation brilliance fromthe possible short-period undulators, indicating theenvelopes of peak brilliance for the odd harmonics up tothe 7th order. For these calculations, we have assumed theminimum gap of 4.5 mm, a total magnet-array length of
0.5 m, and four kinds of period lengths: 10 mm, 12 mm,16 mm, and 20 mm. The nominal beam emittance of 27
nmrad was assumed. Using the 3rd or 5th harmonics of[1] M. Katoh et al., J. Synchrotron Rad. 5, p366 (1998).
[2] M. Izawa et al., J. Synchrotron Rad. 5, p369 (1998).
[3] T. Obina et al., “Global feedback system for Photon
Factory storage ring”, EPAC’98, Stockholm, June
1998, p1726.
[4] K. Tsuchiya et al., “Design and construction of a new
multipole wiggler (MPW#05) at the Photon Factory”,
to be published in Proc. SRI’03, San Francisco,
August 2003.
[5] S. Sakanaka et al., “Improvement in the beam
performance by an RF phase modulation at the KEK
Photon Factory storage ring”, EPAC’00, Vienna, June
2000, p690.
[6] Y. Kobayashi et al., “Injection performance with atravelling wave kicker magnet system at the Photon
Factory storage ring”, PAC’03, Portland, May 2003.
[7] K. Harada et al., “Low emittance optics at the Photon
Factory”, PAC’03, Portland, Oregon, May 2003.