experimental study of the bepcⅡ backgrounds
DESCRIPTION
Experimental Study of the BEPCⅡ Backgrounds. JIN Da-Peng IHEP, Beijing, China Representing the Backgrounds Study Group May 11, 2007, BEPCⅡ IMAC Meeting. Outline. Motivation Radiation detectors arrangement Preliminary results Next to do. Motivation. - PowerPoint PPT PresentationTRANSCRIPT
Experimental Study of the BEPC BackgroundsⅡ
JIN Da-PengIHEP, Beijing, China
Representing the Backgrounds Study GroupMay 11, 2007, BEPC IMAC MeetingⅡ
Outline
Motivation
Radiation detectors arrangement
Preliminary results
Next to do
Motivation1. Take means to protect the detectors from being
damaged
2. Provide good environment for data taking
BEPC is going wellⅡ
Radiation Detectors Arrangement
75cm
1#
2#
3#
4#
5#
2. 22m
6#
3. 31m
1. 65m1. 65m
PI N Di odesRadFETs
30cm
10cm10cm10cm
0#1#2#
3#
4#
10cm10cm
40cm
e+ e-
5#6#7#
Z
X
Y
X
Y
X
Y Y
X
Magnified View
Fork PipeBoth Beams
e- Beam
On Mar. 27, 2007, 2# was moved to 5#
Detectors in the right places
Parameters of theRadiation Detectors
• PIN Diodes– 0.25nA/mrad·s-1
– Damage: 1~10nA/krad– Temp Dep: 1.11times/oC– Accuracy: ~5mrad/s
• RadFETs– Range: 20,000rad– Accuracy: 1.5rad– Freq: 10min
Preliminary Results1#, 2#, 3#, 4# : 75cm from the IP; 6# : 3.31m from the IP.
160nA
80nA
Preliminary Results5# : 2.22m from the IP.
3000nA
More than
1000nA
Preliminary Results
5# detector suffers much more radiation doses than the others, which is more than one fold.
Dominated doses for
5# detector are from the
electron beam.
1#, 2#, 3#, 4# : 75cm from the IP; (Both beams)
6# : 3.31m from the IP; (Upper stream of e-)
5# : 2.22m from the IP. (Upper stream of e-)
Preliminary Results Electron Beam Tuning
1#, 2#, 3#, 4# : 75cm from the IP; 6# : 3.31m from the IP.
Preliminary Results Electron Beam Tuning
5# : 2.22m from the IP.
Preliminary Results Electron Beam Tuning
Dose rates during injections are much higher than steady runs for each detector.
Injections Steady Runs
Dose Rate
(mrad/s)Tens to Hundr
ends0.5 to
about Ten
Int. Dose
(rad/day)
About 100 rad (4#) to
Several Thousands (5#)
Preliminary Results Positron Beam Tuning
0
20
40
60
80
100
120 1# 2# 3# 4# 6#
e+.Curr e-.Curr
Dose Rate
Do
se R
ate
/ n
A
Be
am
Cu
rre
nt /
mA
Time
06:00:002007-03-10
12:00:002007-03-102007-03-10
00:00:00 00:00:002007-03-11
18:00:002007-03-10
0
10
20
30
40
1#, 2#, 3#, 4# : 75cm from the IP; 6# : 3.31m from the IP.
Preliminary Results Positron Beam Tuning
5# : 2.22m from the IP.
1300
1400
1500
1600 5#
e+.Curr e-.Curr
Dose Rate
Do
se R
ate
/ n
A
Be
am
Cu
rre
nt /
mA
Time
06:00:002007-03-10
12:00:002007-03-102007-03-10
00:00:00 00:00:002007-03-11
18:00:002007-03-10
0
10
20
30
40
Preliminary Results Positron Beam Tuning
5# and 6# detectors suffers less doses.
Vertical detectors suffers less doses.
For the horizontal detectors 1# and 3#, Outer Ring(1#) .GT. Inner Ring(3#)
Preliminary Results Double Beam Tuning
0
100
200
300
400
500
600
700 Dose Rate
Curr of e-
Curr of e+
Dose Rate of 2# PIN Diode
Do
se R
ate
/ n
A
Be
am
Cu
rre
nt /
mA
Time00:00:00
2007-03-2812:00:00
2007-03-2800:00:00
2007-03-2912:00:00
2007-03-29
0
10
20
30
40
50
60
70
2# moved to 5#.
Preliminary Results Double Beam Tuning
2# moved to 5#.
Preliminary Results Double Beam Tuning
2# moved to 5#.
Really, Dose Rate at the fork pipe (about 2.2m from the IP) is much higher.
Preliminary Results Int. Dose to the CsI Crystals
0
5
10
15
20
25
30
35
Int.D
ose
/ ra
d
RadFET 0#
RadFET 1#
RadFET 2#
RadFET 3#
Curr of e+
Curr of e-
Int Dose of RadFET at e- Up Stream
Time
00:00:002007-03-28
12:00:002007-03-28
00:00:002007-03-29
12:00:002007-03-29
0
10
20
30
40
50
60
70
Be
am
Cu
rre
nt /
mA
30cm
40cm
50cm
60cm
Preliminary Results Int. Dose to the CsI Crystals
40cm
50cm
60cm
0
5
10
15
RadFET 5#
RadFET 6#
RadFET 7#
Curr of e-
Curr of e+
Int Dose of RadFET at e+ Up Stream
0
10
20
30
40
50
60
70
Int.D
ose
/ ra
d
Be
am
Cu
rre
nt /
mA
00:00:002007-03-28
12:00:002007-03-28
00:00:002007-03-29
12:00:002007-03-29
Preliminary Results Int. Dose to the CsI Crystals
The maximum Int. dose at the position of the inner most CsI crystals is about 10rads/day, which is about 10 times that of the design value.
Injections bring much more doses.
The total Int. dose from the electron beam is higher than that from the positron beam.
Preliminary Results Int. Dose at the fork pipe
0
1000
2000
3000
4000
5000
Int Dose
Curr of e-
Curr of e+
Time
Int.D
ose
/ ra
d
00:00:002007-03-28
12:00:002007-03-28
00:00:002007-03-29
12:00:002007-03-29
Int Dose of RadFET 4#
0
10
20
30
40
50
60
70
Be
am
Cu
rre
nt /
mA
Preliminary Results Int. Dose at the fork pipe
In the previous measurement, the Int. dose is .GT. 3000rads/day, which is mainly due to e- injections.
In some cases, one turn injections can bring hundrends to one thousand rads Int. doses.
Preliminary Results Beam Loss Monitors
IPNo. 48 No. 72
BLMs are sensitive with charged particles
e+ e-
Preliminary Results Beam Loss Monitors
Preliminary Results Beam Loss Monitors
Preliminary Results Beam Loss Monitors
Preliminary Results Beam Loss Monitors
Why so high dose?
The accelerator needs to be well tuned, since we have just started.
In the currently used vacuum chambers, the radius near the fork pipe is smaller than the design values and makes here the bottleneck of the storage ring.
Collimators not installed.
Next to do
Further understand the results from the PIN Diodes, FETs and BLMs;
Deal with the backgrounds seriously and push ahead the manufacture and installation of the collimators;
Your suggestions???
Thanks!