Slow Positron Facility at High Energy Accelerator Research Organization (KEK) is a user dedicated facility with an energy-tunable (0.1 - 35 keV) slow positron beam created by a dedicated ∼ 50 MeV linac. It operates in a short pulse (width 1-12 ns, variable, 5×106 e+/s) and a long pulse (width 1.2 µs, 5×107 e+/s) modes of 50 Hz. High energy positrons from pair creation are moderated by reemission after thermalization in W foils. The reemitted positrons are then electrostatically accelerated to a desired energy up to 35 keV and magnetically transported. A pulse-stretching section (pulse stretcher) is installed in the middle of the beamline. It stretches the slow positron pulse for the experiments where too many positrons annihilating in the sample at the same time has to be avoided. Four experiment stations for TRHEPD (total-reflection high-energy positron diffraction), LEPD (low-energy positron diffraction), Ps (positronium negative ion), and Ps-TOF (positronium time-of-flight) experiments are connected to the beamline branches, SPF-A3, SPF-A4, SPF-B1 and SPF-B2, respectively. Recent results of these stations are briefly described.

1.
A. P.
Mills
, Jr.
, in
Positron Solid State Physics
, edited by
W.
Brandt
and
A.
Dupasquier
(
North-Holland, Amsterdam
,
1983
), pp.
432
509
.
2.
P. J.
Schultz
and
K. G.
Lynn
,
Rev. Mod. Phys.
,
60
,
701
779
(
1988
).
3.
C.
Hugenschmidt
,
Surf. Sci. Rep
7
,
547
594
(
2016
).
4.
T.
Hyodo
, et al,
J. Phys.: Conf. Ser.
791
,
012003-1
8
(
2017
).
5.
T.
Hyodo
, et al,
J. Phys.: Conf. Ser.
262
,
012026-1
5
(
2011
).
6.
K.
Wada
, et al,
Eur. Phys. J. D
,
66
:
37-1
4
(
2012
).
7.
A.P.
Mills
, Jr.
, et al,
Phys. Rev. Lett.
41
,
1076
1079
(
1978
).
8.
A.P.
Mills
, Jr.
,
Appl. Phys.
23
,
189
191
(
1980
).
9.
M.
Maekawa
, et al,
Eur. Phys. J. D
68
:
165
,
1
6
(
2014
).
10.
A.
Ichimiya
,
Solid State Phenom.
28-29
,
143
148
(
1992
).
11.
A.
Kawasuso
and
S.
Okada
,
Phys. Rev. Lett.
,
81
,
2695
2698
(
1998
).
12.
Y.
Fukaya
, et al,
J. Phys.: Conf. Ser.
443
,
012068
,
1
6
(
2013
).
13.
Y.
Fukaya
, et al,
Appl. Phys. Express
7
,
056601
(
2014
).
14.
I.
Mochizuki
 et al,
Phys. Chem. Chem. Phys.
18
,
7085
7092
(
2016
).
15.
A.
Fujishima
, et al,
Surf. Sci. Rep.
63
,
515
582
(
2008
).
16.
M. A.
Henderson
,
Surf. Sci. Rep.
66
,
185
297
(
2011
).
17.
A.
Ichimiya
,
Jap. J. Appl. Phys.
22
,
176
180
, Jap. J. Appl. Phys. 24, 1356 (
1985
).
18.
Q.
Wang
 et al,
Phys. Rev. Lett.
113
,
266101-1
5
(
2014
).
19.
A.K.
Geim
,
Science
324
1530
1534
, (
2009
).
20.
G.
Giovannetti
, et al,
Phys. Rev. Lett.
101
,
026803-1
4
(
2008
).
21.
M.
Batzill
,
Surf. Sci. Rep.
67
,
83
115
(
2012
).
22.
P.L.
Silvestrelli
and
A.
Ambrosetti
,
Phys. Rev. B
91
,
195405-1
9
(
2015
).
23.
24.
Y.
Fukaya
, et al,
Phys. Rev. B
88
,
205413-1
4
(
2013
).
25.
P.
Vogt
 et al,
Phys. Rev. Lett.
108
,
155501-1
5
(
2012
).
26.
Y.
Fukaya
, et al,
2D Materials
,
3
,
035019-1
8
(
2016
).
27.
I. J.
Rosenberg
, et al,
Phys. Rev. Lett.
44
,
1139
1142
(
1980
).
28.
T. N.
Horsky
, et al,
Phys. Rev. Lett.
62
,
1876
1879
(
1989
).
29.
C. B.
Duke
and
D. L.
Lessor
,
Surf. Sci.
225
,
81
86
(
1990
).
30.
S. Y.
Tong
,
Surf. Sci. Lett.
457
,
L432
L436
(
2000
).
31.
K.
Wada
 et al,
to be published in e-Journal of Surface Science and Nanotechnology (e-JSSNT): Proceedings of ISSS-8
(
2018
)
32.
S. Y.
Tong
, et al,
Phys. Rev. Lett.
69
,
3654
3657
(
1992
).
33.
S. Y.
Tong
and
H.
Wu
,
J. Phys.:Condens. Matter
14
,
1231
1236
(
2002
).
34.
J. A.
Wheeler
,
Ann. N. Y. Acad. Sci.
48
,
219
238
(
1946
).
35.
A. P.
Mills
, Jr.
,
Phys. Rev. Lett.
46
,
717
720
(
1981
).
36.
Y.
Nagashima
and
T.
Sakai
,
New J. Phys.
8
,
319-1
7
(
2006
).
37.
Y.
Nagashima
,
Phys. Rep.
545
95
123
(
2014
).
38.
H.
Terabe
, et al,
New J. Phys.
14
,
015003-1
6
(
2012
).
39.
K.
Michishio
, et al,
Appl. Phys. Lett.
100
254102-1
4
(
2012
).
40.
K.
Michishio
, et al,
Phys. Rev. Lett.
106
153401-1
4
(
2011
).
41.
A. P.
Mills
, Jr.
Phys. Rev. A
24
3242
3245
(
1981
).
42.
A. K.
Bhatia
and
R. J.
Drachman
,
Phys. Rev. A
28
2523
2525
(
1983
).
43.
Y. K.
Ho
,
Phys. Rev. A
19
2347
2352
(
1979
).
44.
J.
Botero
, and
C. H.
Greene
,
Phys. Rev. Lett.
56
,
1366
1369
(
1986
).
45.
A. K.
Bhatia
,
Y. K.
Ho
,
Phys. Rev. A
42
,
1119
1122
(
1990
).
46.
A.
Igarashi
, et al,
New J. Phys.
2
,
17.1
17.14
(
2000
).
47.
K.
Michishio
, et al,
Nature Communications
7
,
11060-1
5
(
2016
).
48.
K.
Michishio
, et al,
Nucl. Instrum. Meth. Phys. Res. A
785
,
5
8
(
2015
).
49.
Y.
Nagashima
, et al,
Phys. Rev. B
58
,
12676
12679
(
1998
).
50.
H.
Terabe
, et al,
Surf. Sci.
,
641
,
68
71
(
2015
).
51.
S.
Iida
, et al,
J. Phys.: Condens. Matter
28
,
475002-1
4
(
2016
).
52.
T.
Yamashita
, et al,
Nucl. Insrum. Meth. Phys. Res. B
387
,
115
118
(
2016
).
This content is only available via PDF.