2013/05/20

2013/05/20

Run Diary

1105	Hook up leak checker and turn it on.
1130	Calibrated leak checker.
1132	Opened leak checker up to vent and pumped air out of the line.
1205	Background stabalized to 4.21E-10 mbar l/s. Opened the speedy valve to vent and isolated the He-4 pump.
1215	Leak rate has stayed steady at 1.35E-7 mbar l/s. Opened valve 13B connecting leak checker to He-3 pump. Leak checker immediately overloaded. G2 dropped below 900 mbar. G1 rose to 450 mbar. Closed valve 13B.
1220	Closed the speedy valve to vent and reconnected He-4 pump to vent. G1 dropped to 3.3 mbar.
1223	Checked to make sure the leak checker is still calibrated, reopened leak detector to vent.

Stripline Production

Previous Updates

Stipline designs.

Testing of CuBe wires and prototype cable.

Current Status

We were able to commission all 38 manganin wires. The pinouts for the cable are given below, as well as the wire pairs.

Table 1: Pinouts for MIT Cable.
Signal	Bulkhead D pin	Stripline D socket	Material	Wire Pair	Micro D pin	FET Card Pin
QET A return	1	17	manganin	1	1	2
Feedback B	2	16	manganin	2	36	14
QET A	3	15	manganin	1	2	15
SQUID bias A	4	14	Cu-Be	3	37	16
QET C return	5	13	manganin	19	4	4
Feedback D return	6	12	manganin	5	3	5
QET C	7	11	manganin	4	22	18
SQUID bias C	8	10	Cu-Be	6	24	19
QET C return	9	9	manganin	4	38	7
QET C return	10	8	manganin	20	5	8
Qo bias	11	7	manganin	16	40	21
Qo drain	12	6	Cu-Be	7	27	22
QET A return	13	5	manganin	21	25	10
QET A return	14	4	manganin	21	26	11
Qi bias	15	3	manganin	17	44	24
Qi drain	16	2	Cu-Be	8	47	25
QET A return	17	1	manganin	22	8	13
Feedback B return	18	33	manganin	2	19	1
SQUID bias B	19	32	Cu-Be	9	35	27
SQUID A return	20	31	Cu-Be	3	20	3
Feedback A return	21	30	manganin	10	33	41
Feedback D	22	29	manganin	5	21	17
SQUID bias D	23	28	Cu-Be	11	15	30
SQUID C return	24	27	Cu-Be	6	23	6
Feedback C return	25	26	manganin	12	32	44
LED 2	26	25	manganin	18	6	20
Qo source	27	24	Cu-Be	7	28	33
QET C return	28	23	manganin	20	9	9
QET B return	29	22	manganin	13	49	47
Qo feedback	30	21	manganin	16	41	23
Qi source	31	20	Cu-Be	8	48	36
QET A return	32	19	manganin	23	7	12
QET B return	33	18	manganin	22	11	50
SQUID B return	34	50	Cu-Be	9	51	39
QET B	35	49	manganin	19	17	26
QET D return	36	48	manganin	14	18	40
Feedback A	37	47	manganin	10	34	28
QET D	38	46	manganin	14	16	29
SQUID D return	39	45	Cu-Be	11	50	42
QET D return	40	44	manganin	13	14	43
Feedback C	41	43	manganin	12	31	31
LED 1	42	42	manganin	18	39	32
QET D return	43	41	manganin	24	30	45
QET D return	44	40	manganin	24	29	46
FET heater +	45	39	manganin	15	46	34
FET heater -	46	38	manganin	15	45	35
QET B return	47	37	manganin	25	13	48
QET B return	48	36	manganin	25	12	49
FET Tsense +	49	35	manganin	23	10	37
Qi feedback	50	34	manganin	17	43	38
Ground			Cu-Be		42

All wires have length 3.3m in case the extra length is needed. Once the wire pairs were soldered to the 50-pin connector the cables were then bundled and wrapped in PTFE tape. Several layers of Kapton tape were added to give the bundle significant girth to prevent movement once the bundle was secured in the connector clamp, as shown in Figures 1a and 1b.

Fig. 1a and Fig. 1b: Connector clamp with wire bundle, to be connected to 300K

We decided that arranging the traces in a flat, taped stripline would be the optimal method to secure the wires and reduce the risk of wires breaking or shorting due to catching or rubbing on anything within the fridge. With the connector secured, the wires are gently pulled tight and arranged in a single layer on a 1“ wide piece of Kapton tape. Once all 25 pairs have been secured on the tape, another piece of Kapton tape is placed on top. Due to the limited working space inside the clean room, only small lengths of wire can be taped at a given time.

Fig. 2: Secured connector and initial stretch of stripline

Fig. 3a and Fig 3b: Close up of single layer of 25 wire pairs on Kapton tape

As mentioned before, limited working space has greatly hindered our efficiency. To save on space and minimize wire tangling, wires are loosely hung from hooks as shown in Fig. 4. Despite this organization, tangled and kinked wires continue to be a time-consuming issue.

Fig. 4: Wire organization system

Fig. 5a and Fig 5b: Current length of stripline

Currently, about 3 feet of stripline has been arranged in a single layer and taped. Once the entire stripline line has been taped, an additional layer of Kapton tape and one layer of 1” wide copper tape will be added to each side of the stripline to protect the traces from breaking or shorting inside the fridge. The stripline will then be placed inside the baffles between striplines 27 and 21.

Cricket's Obituary

Cricket the fish, age unknown, of Minneapolis, MN, died unexpectedly Tuesday, May 14, 2013, in his fish bowl. Preceded in death by his brother Livingston. Survived by his mother and coworkers. Cricket was known to be a passionate member of the CDMS dark matter search. He was often seen working in lab long after everyone else had gone home. As per his request, a viking burial ceremony was performed in his honor on Wednesday, May 15.