1. SAMURAI Si detector Requirements overview
Detector team
M. Kurokawa
N. Iwasa, A. Taketani, Y. Togano, H. Murakami, T. Motobayashi, K. Yoneda
Requirements overview
Development of readout circuit
(ASIC chip for preamplifier)
Summary (present status and future subjents)

2. Requirements overview on silicon detector
both of them are analyzed by SAMURAI
proton
Heavy Ion
(z <50)
0.5O
secondary target
(Pb etc.)
Si detectors
RI beam from BigRips
Effective area of Si detector > 9 cm  9 cm
Position resolution dx ~ 0.2 mm, dy ~ 0.2 mm
6 pieces of GLAST Si detectors are necessary
(x, y, left and right angle ambiguity)  2
(already available)

3. Specification of the GLAST Si Ref. ) T. Ohsugi et al
Specification of the GLAST Si Ref.) T. Ohsugi et al., “Design and properties of the GLAST flight silicon micro-strip sensors”, Nucl. Instr. and Methods, A541 (2005)
single sided strip detector
manufactured by HPK
500 pF
50 MW
6 in.
--> 325 mm
to read leakage current
of each strip
capacitance/strip pF
Interstrip capacitance 5 pF

4. Requirements overview on readout circuit
total number of strips is around 2500
dynamic range has to be larger than 5000 to detect
proton (z = 1, 10 fC) and heavy ion (z < 50, 25 pF)
(and its pile up)
Employment of ASIC(Application Specificated Integrated Circuit) has been considered because of I.
Architecture of HINP16C ASIC chip corresponds to our
purpose basically.
Collaboration is very helpful for our development, but some
of the works are of our own subjects. For example,
enlargement of the dynamic range.
Ref.) G. L. Engel et al., “A multi-channel integrate circuit for use in low-
and intermediate-energy nuclear physics---HINP16C”, Nucl. Instr. and
Methods A573 (2007)

5. Enlargement of dynamic range by 10 times
capacitive division
Ref.) N. Uematsu and S. Nishimura, “Development of silicon strip detector with wide-dynamic-range readout system from 20 keV to 4 GeV”, RIKEN Accel. Prog. Rep. 41, (2008) 151.
saturation suppression by making use of
the relation Vout = Q / Cf
Detail will be discussed in following talk
by Murakami-san
Chigh
3.6 fC ~ 36 pC
high gain(for proton)
useful for 4 fC ~ 4 pC
Qin
4 fC ~ 40 pC
CSP
Clow= Chigh / 10
low gain(for HI)
useful for 40 fC ~ 40 pC
CSP
0.36 fC ~ 3.6 pC Cd
Vout
This function can be　implemented in ASIC chip?
training course at KEK
to learn how to make it
with saturation suppression
Without saturation
suppression
Qin

6. Threshold for starting ASIC
Initial cost
Performance (basically, ASIC consists of enormous
number of MOSFETs)
Was not for signal channels of only a few hundreds
Was for limited purpose, to find fired channel, for example.
Not commonly used for experiment involving detection of heavy ions
at low and intermediate-energy region
shuttle service
Library(accumulated know-how)

7. Introduction of some techniques established in MOS analog circuit
increasement of the open loop gain in HINP16C case
as an example
Vgs1’
Vds2 Id M2
Vgs2
DId M1 Id
Vgs1
w/l--> small
Vgs2 = 1.4 V
w/l--> large
Vgs1 = 1.1 V
> 1.4 M1
Vds1 Vd
0 --> -2 V
out
-DVgs1(= DVds2)

8. Prototype chip RIKENDGCSP
Cf = 1.8 pF
“Schematic diagram”
Chigh
Rf corresponding to 50 MW -A
Cf = 1.8 pF
Clow
Rf corresponding to 50 MW -A
RIKENDGCSP
w/l--> small
w/l--> large
w/l--> small
Open loop gain (A) is large ~ 82 dB
by employing the technique shown
in previous slide
w/l--> large
w/l--> large
Output: +0.5 ~ -2.0 V
input
w/l--> small

9. Why we need to increase the open loop gain?Cf
Chigh
Zhigh = 1 / (Chigh s) + Zf/A -A
Pulse heights at t = 1 ms
are estimated by simulation
code HSPICE and are plotted
below. Cf
Clow= Chigh / 10 -A
Zlow = 1 / (Clow s) + Zf/A
A --> ∞ is ideal also for rising time
A = > (82 db) by using cascode connection of current mirrors
A = 500
A = 10000
suppression circuit begins to work
low gain
high gain
ratio of the slope = 2.6
Chigh (= 5 nF) : Clow (= 500 pF) = 1 : 10

10. Prototype chip RIKENDGCSP II
size : ~1.6 mm  1.2 mm
ch num.: high gain output 1 ch, low gain output 1 ch
function: preamplifier
Will be ready in Feb. 2010 ?
size :3 mm  3 mm
ch num.: high gain output 8 ch, low gain output 8 ch
function: preamplifier, shaping amplifier, (peak hold, multiplexer,,,,,,,)
cost: 1000,000 yen for 20 chips (160 pairs)?

11. Ideas for next version Another circuit to suppress the saturation
Preparation of spare channel for strips at central position
CSA
input

12. Ideas for another application of ASIC
x, y
“highly segmented Ge detector”
Position information can be extracted even for
multiple scattering
increase of signal channels
ASIC
“segmented Ge detector” g
CSA
SCA
(x, y, z)
CSA
CR2 - RC4
Comp.
information on z
CSA
SCA
information on x, y
Wave form can be stored with sequential capacitive arrays
Ref.) MATACQ
2 G samples/s z

13. Present status and subjects of SAMURAI Si
readout circuit
Technique to enlarge the dynamic range will be
established soon with the ASIC chip RIKENDGCP.
“characteristics of RIKENDGCP”
dynamic range: 4 fC ~ 40 pC
open loop gain: 82 dB
saturation suppression function:employed
The performance is verified with SPICE simulation.
The first prototype will be tested in Feb

14. cooling system of the circuit
advantage --> Number of feed through connectors can
be significantly suppressed
16 ch  2 = 32 ch
1.5 W/board
32 ch 16 = 512 ch
Cf.) GLAST Si: 384 2 ch / piece
Example of HINP16C
cross talk
How many strips are fired (higher than proton
threshold) when HI is implanted?
any way
for suppression?
500 pF
2 pF
5 pF
5 pF