SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Additional information (Details) $ in Thousands		12 Months Ended
	Sep. 27, 2021 USD ($)	Sep. 30, 2021 USD ($)	Sep. 30, 2020 USD ($)	Sep. 30, 2019 USD ($)
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES
Total revenue recognized		$ 89,605	$ 60,469
Restricted cash		18,000
Allowance for doubtful accounts		668	561
Depreciation and amortization		6,268	4,074
Goodwill		51,927	4,368	$ 3,617
Total amount of intangible assets subject to amortization		24,233	4,261	$ 2,883
Long-term debt		54,922
Contingent consideration		640
Amount of gain from the fair value		8,362
Long-term debt		170,323	25,052
Fair value of the conversion		54,922
Research and development expense		405	617
Startup costs		1,477	333
Debt issuance costs		6,458	235
Debt issuance costs paid		6,223	127
Straight-line rent per month		53
Variance between the straight-line rents recognized and the actual cash rents received		0
Convertible Senior Notes
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES
Long-term debt		54,922
Amount of gain from the fair value		8,362
Principal amount	$ 140,000
Annual Interest Rate (as a percent)	3.25%
Settlement period	13 days
Additional principal amount	$ 15,000
Long-term debt		131,673
Fair value of the conversion		54,922
Convertible Senior Notes | Other Income
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES
Amount of gain from the fair value		$ 8,362
Convertible Senior Notes | Measurement input - price volatility
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES
Measurement input		81.1
Convertible Senior Notes | Measurement input - risk-free interest rate
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES
Measurement input		1.195
Convertible Senior Notes | Measurement input - maturity period
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES
Maturity period (in years)		6 years 14 days
Building and Building Improvements | Minimum
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES
Useful life of property, plant and equipment		34 years
Building and Building Improvements | Maximum
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES
Useful life of property, plant and equipment		40 years
Machinery and Equipment | Minimum
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES
Useful life of property, plant and equipment		5 years
Machinery and Equipment | Maximum
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES
Useful life of property, plant and equipment		10 years
Furniture and Fixtures
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES
Useful life of property, plant and equipment		10 years
Royalty revenue
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES
Total revenue recognized		$ 377	$ 641